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WORK BOOK IN PHYSICAL GEOGRAPHY

THE LITHOSPHERE

Define the term “lithosphere”

This refers to the solid outer most layer of the earth, surrounding the mesosphere

What two differences can be noticed between the continental crust and the oceanic

crust?

The differences between continental crust and oceanic crust are as follows:

i. The continental crust is the upper part which forms continents while as the

oceanic crust is the lower part which forms oceans.

ii. The continental crust is made up of Granitic rocks, these rocks are rich in

Silica (Si) and Aluminum (Al) hence the layer is also called SIAL. This is in

contrast with the oceanic crust which is made up of Basaltic rocks. Such rocks

are rich in Silica (Si) and Magnesium (Ma) hence the oceanic crust is also

called (SIMA).

Describe the characteristics of the following:

(a) Core (b) Mantle (c) crust

The characteristics of the core

a. It is mainly made up of Iron (Fe) and Nickel (Ni) hence it is called

NIFE

b. It is the most interior layer of the earth, which is also called

Barysphere

c. It is divided into outer core and inner core

d. It experiences the highest temperature of about 1972

0

C and subjected

to high pressure

e. It is the source of gravitational force

The characteristics of the mantle are as follows:

a. It is part of the earth which is found between the core and the crust

b. It is one of the largest layers about 2900 Km thick

c. There are a lot of convection currents in terms of the movement of

materials. Such movements are responsible for plate motion.

d. It is made up of dense rocks which are rich in Olivine and silicate

minerals

e. It is Mainly made up of magma which is capable of flowing especially

in the upper part

The characteristics of the lithosphere or the crust are as follows:-

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a. It is made up of two parts namely, the continental or upper crust and

the oceanic or lower crust

b. It is the solid outermost layer which surrounds the mantle of the earth

c. It is separated from the mantle by a boundary called Moho discontinuity

d. It is the thinnest layer ranging from 5 Km to 48 Km in thickness

e. It is consists of thin, loose layer known as soil.

With the help of a diagram, explain the term “isostacy”

This is the process whereby continental crust appears as if it is floating on the oceanic

crust. This happens because the granitic rocks which are rich in Silica and alumina

that make up the continental crust are less dense with an average density of 2.7g/cm

3

.

The basaltic rocks that are rich in silica and Magnesium which make up the oceanic

crust are heavier with an average density of 3.0 g/cm

3

. Since the continental crust or

SIAL is lighter than the oceanic crust (SIMA), the continents can be said to be

“floating” on a sea of denser SIMA. The diagram below shows this.

Continent

Ocean

SIAL

Upper mantle Moho discontinuity

Study the figure below and answer the questions that follow

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Name the Zones marked A,B, and C

A= Lithosphere or crust

B= Mesosphere or mantle

C= Barysphere or crust

Why does B float on C?

This is because part C is very dense and metallic since it has a large density than B, it

is able to support part B making as if is floating on C.

State the names given to the boundaries between A and B; B and C

A and B = Moho discontinuity

B and C = Gutenberg discontinuity

Explain two characteristics of part labeled B

i. It is very warm and voluminous covering about 82.5% of the earth’s volume

ii. It is kept in plastic state by heat and pressure

iii. Movements of materials are conventional

C

B

A

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Draw and label the internal structure of the earth (5) (1993) (2001) (2005)

The internal structure of the earth is made up of three main parts namely the crust

which is also called Lithosphere, the mantle which is also called the mesosphere and

the core which is also called the barysphere. The crust is the outermost and the

thinnest layer, the mantle is the middle and the largest layer, the core is the innermost

layer. Between the layers are boundaries. The diagram below shows the internal

structure of the earth.

Which part of the internal structure of the earth contains continents? (2001) (1 mark)

The upper part, also called continental crust

How important is the mantle in relation to the crust (2001) (1 mark)

i. As the mantle is denser than the crust, it supports the crust

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ii. It provides magma which when flows to the crust results into the formation of

many features such as volcanic mountains.

Mention the two minerals that are found in the inner most layer of the internal

structure of the earth (2005)

i. Iron (Fe)

ii. Nickel (Ni)

Explain why most parts of the internal part of the earth is in a liquid state (2005) (2

marks)

This is due to high temperatures and high pressure. The combination of the two melt

the rocks, turning them to molten materials called magma, which is a semi- liquid

state

The core is made up of two main parts, the inner core and the outer core. Why is it that

the outer core is in a liquid state while the inner core in a solid state? (3 marks)

The inner core is made up of materials with a very high melting point. Thus, even the

temperature is very high in the inner core; the materials are still in a solid state

because such materials require even a higher temperature for them to melt. This

makes materials in the inner core still to be in a solid state. In contrast, materials that

are found in the outer core require a lower melting point. This makes the temperature

experienced to be enough to melt the rocks which then appear in a semi molten or

liquid state.

CONTINENTAL DRIFT THEORY

Describe Wagner continental drift theory

This is the theory which explains about the movement of continents. The theory

explains that at one point in time, the earth was made up of a single supper continent

called Pangea. This Pangea was surrounded by a big ocean called Panthalasa. The

theory goes on to say that, suddenly the Pangea split into the northern land mass

called Lauresia and the southern landmass called Gondwanaland. Furthermore, these

landmasses drifted gradually changing their positions. The last stages involved north

America joining to South America, India moving away from Australia and joining to

Asia while Australia remained as island. The person who put forward this theory was

a German scientist called Alfred Wegner.

What evidence could you look for to prove that continents have drifted across the

earth?(2006)

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i. The southern continents fit in a jig-saw puzzle, that is, they can be easily fit if

brought together. For example, the continent of Africa and South America.

This shows that the continents were at first joined together

ii. Magnetism of ancient rocks (paleomagnetism) indicates that the continents

were once a single continent. Rocks are magnetized in the direction of the

magnetic north when solidifying. All ancient rocks on all continents show

similar magnetism pattern.

iii. There is almost identical geological sequence of rock layers in south Africa,

Deccan plateau (India), plateau of south America and Antarctica

iv. West African rocks and those of Brazil are similar in age structure

v. Fossilized trees in Antarctica show that the land mass might have experienced

climatic conditions different from those of today. The present day Antarctica is

frozen and covered with ice.

vi. Folded mountain ranges of Argentina are similar in structure and age to the

folded cape ranges of South Africa.

Why do you think it would be difficult for many people to believe wegners theory of

continental drift, explain three points?

i. The theory does not explain what happened so that the Pangea should break

apart. It does not really explain what caused the drifting process

ii. The position of the magnetic poles seems to have wondered all over the earth.

A path of a apparent polar wondering measured in North America was

different from that in Europe

iii. Fossils of plants might have been spread throughout the drifted continents by

wind or ocean currents and not by the drifting process

iv. Similar shapes in the coastlines are as a result of water erosion that shapes

them the way they are, and not that at first were joined together

v. The separation of the continents has been strongly opposed on physical

grounds.

The figure below shows continents trying to move to various positions

C

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B

A

What name is given to the process that has moved them to that present positions today

It is called continental drift

What feature is formed between continents A and B as they split apart?

It is a mid-Atlantic Ocean ridge

PLATE TECTONIC THEORY

Define the term crustal plates

These are rigid slab-like structures that make up the lithosphere

With examples give two main types of plates

i. Continental plates, examples include North American plate, African plate,

South American plate, Eurasian plate

ii. Oceanic plates. Examples include the Pacific plate; the Arctic plate

Explain two differences between these two main types of plates

i. Oceanic plates form the oceanic floor while as continental plates contain

continents or landmasses

ii. Oceanic plates are denser because they contain heavier basaltic rocks,. This is

in contrast with the continental plates which are lighter because they contain

granitic rocks which are lighter.

Study the figure below which show the plates of the earth’s crust and answer the questions

that follow:

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1. Name the plates A-I

A= Eurasian plate

B= Carribean plate

C= Nazca plate

D= Phillipine plate

E= Australian plate

F= African plate

G= North American plate

H= south American plate

I= Pacific plate

2. Name the ridges marked K,L and M

K= Mid Atlantic ocean ridge

L= Mid Indian ocean ridge

M= Mid pacific ocean ridge

3. Mention two geological processes that usually take place at ridge marked K

i. Sea floor spreading as the materials upwell from the mantle

ii. Oceanic volcanic eruption as magma comes out as a result of the divergent

boundary

iii. Earthquakes which are triggered by the materials when they upwell from the

ground

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4. What drives the movement of plates across the surface?

Convectional currents that operate within the upper part of the mantle cause plate

motion. These convection currents operate laterally and cause the plates to break

apart, diverge or collide. The diagram below shows this cause of plate motion.

How do crustal plates contribute to the formation of the following features:

a) Oceanic or submarine ridges

b) Fold mountains

c) Volcanoes

d) Trenches

A. Tectonic activities lead to the formation of many features. One of such feature is

the formation of the oceanic ridges. These are ridges which are formed under the

water or oceans. They are formed when plates move away from each other in a so

called divergent boundary. In this boundary, the crust between the plates breaks

forcing the magma out to the surface of the seafloor. The magma then spreads out

in a new crust in a ridge form. Examples of such ridges are the mid Atlantic, mid

Indian and mid Pacific Ocean ridges which do not rise above the level of the

oceans. The diagram below shows how the mid marine ridges are formed:

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B. Oceanic Island is another feature formed through tectonic activity. Oceanic

islands rise above the level of the water. They can either form through

compressional forces or tensional forces. When formed through compressional,

the crust becomes folded up as the plates move towards each other. The fold rises

above the level of the water and form an island. The diagram below shows this:

When formed through tensional forces, the plates diverge or move away from each

other. When this happens, a hole is formed through which magma rises to the top

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level of the water. Magma then produces above the surface of the water and finally

cools and solidifies to form a volcanic island. The diagram below shows this:

C. Tectonic activities contribute to the formation of volcanoes. Rocks under the

earth’s crust are subjected to high temperatures and pressure. The combination of

these two make rocks to melt and turn semi molten materials called magma. When

plates move away from each other in a divergent boundary a vent is left. This

makes magma to flow through on to the earth surface, building come shaped

mounds called volcanoes.

Volcanoes also form in convergent boundaries. When plates collide, one dives

under the other. The plate that dives is subjected to very high temperatures and

melts to become magma. This magma then rises through the cracks produced in

collision and form volcanoes. Furthermore, the plate that dives, disturbs the

magma which is already there. This makes the magma to be squeezed and to rise

through the cracks thereby forming volcanoes.

D. Another important result of tectonic activity is the formation of oceanic trenches.

Oceanic trenches are the deepest parts of an ocean. These are mainly formed in

the convergent boundaries where plates move towards each other. When this

happens one plate is forced to dive under the other. For example, if it is

continental and oceanic, the oceanic plate dives under the continental as it is

denser. This happens in the subduction zone where by the margins of the oceanic

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plates are bent down into the mantle as the continental plate “rides up” over

them. This causes an ocean deep which is called a trench. Examples of trenches

include Peru, Java, Marianas, and Tonga. The diagram below shows trench and

volcano being formed in the convergent boundary.

E. Tectonic activity also results into the formation of earthquakes. These are

vibrations produced in the earth’s crust. These usually occur in plate boundaries

such as convergent, divergent and transform or tear. The force created during

plate motion makes the land to shake.

What is meant by each of the following terms :

a) Subduction

b) Constructive plate boundary

c) Destructive plate boundary

Subduction: This is an area in the convergent boundary where one plate dives under the

other. This usually happens when the collision is between oceanic plate and continental

plate. Being denser, the oceanic plate dives under the continental plate.

Constructive plate boundary: this is a diverging plate boundary whereby plates separate or

move away from each other. It is known as constructive because when plates separate, new

crust is formed through the upwelling of materials from the mantle.

Destructive plate boundary: the boundary whereby plates move towards each other and

collide. It is also called convergent boundary. It is referred to as destructive because when

plates collide, part of the crust is destroyed especially when one plate dives under the other.

Explain why British earthquakes are very rare and of low intensity, while Japanese

earthquakes are common and are often very destructive?

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Earthquakes are mainly associated with plate margins. British earthquakes are rare

and of low intensity because Britain is far from the plate margins. In contrast, Japan

lies within the convergent boundary where a lot of force Is generated. This makes

Japanese earthquakes to be common and very destructive.

Explain the reason why the Andes mountain suffer from explosive volcanic activity and

powerful, deep focus earthquakes

This is because the Andes lie in the convergent boundary between the Nazca plate and

the South American plate. This makes the area to experience a lot of earthquakes and

volcanoes which are as a result of the convergent boundary

Study the map below which shows the ages volcanoes in million years in the Atlantic

ocean and answer the questions that follow

What happens to the age of volcanoes as you move away from the mid Atlantic ridge?

The volcanoes tend to increase in the age as someone moves away from the mid-

Atlantic Ocean ridge.

Explain why this pattern develop

This shows that very close to the ridge, volcanoes take place frequently as a result of

the separation of plates than far from the mid oceanic ridge.

MOUNTAIN BUILDING PROCESSES

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What is a fold?

This is a bend in the crust caused by expression forces exerted by the earth movements.

Below is a diagram of a fold. What name is given to parts labeled A, B and C

The following are the names:

A= Anticline

B= Limb

C= Syncline

With the aid of a diagrams describe the following types of folds:

a) An asymmetrical fold

b) An over fold

c) An over thrust fold

a. An asymmetrical fold is a type of a fold whereby one limb is steeper than the other4.

This happens when compression forces on one side are greater than the other side.

The diagram below shows this:

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b. An over fold is a type of a fold whereby one limb is pushed over the other. This is

caused by the application of more compression force on asymmetrical fold, with more

force from one side than the other.

c. An over thrust fold, also called thrust fold is a type of a fold in which there is a line of

fracture. In addition, the limb of the fold is thrust forward over the other limb and

there is the displacement or rock layer.

Explain the following terms:

i. Orogenesis

ii. Epeirogenic

iii. Orogenic

i. Orogenesis is the tern used to describe all the processes involved in the building

of mountains.

ii. Epeirogenic is the vertical movement of the earth’s crust

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iii. Orogenic: movements done in the earth’s crust. It involves the horizontal or

lateral movements in the earth’s crust.

What are the effects of the following movements in the earth’s crust:-

a. Epeirogenic movements

These are vertical movements of the earth’s crust. These mainly cause rift valleys and

block mountains. The land sinks downwards.

b. Orogenic movements

These are horizontal or lateral movements. These are responsible for mountain

buildings such as Fold Mountains, volcanoes.

With the aid of a labeled diagram describe how mountains are formed

Fold mountains consist of masses of folded sedimentary rocks with a thickness of over

12 Km. these mountains are formed in convergent plate boundaries. In these

boundaries, plates move towards each other, collide, a temporally sea known as a

geosynclines is formed. Erosion takes place on the sides of the continents and

deposition takes place in a geosynclines. Due to the movement of plates, the area

between the plates becomes folded up. This is also as a result of the formation of

sedimentary rocks which then bend upwards. In the formation of such mountains,

earthquakes and volcanoes also form. Examples of mountains formed in this way are

the Rockies in North America. These were formed when the Pacific plate collide with

the Indo-Australian plate; the Atlas in North Africa, formed when the Africa plate

collided with the Eurasian plate, the Andes in South America, formed when the Nazca

Collide with the South American plate.

The diagrams below show how in general Fold Mountains are formed.

In this stage the continental blocks move towards

each other through compression force. Plates

collide and produce a temporally sea called a

geosynclines. Deposition takes place.

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As the continental blocks approach each other, the

sedimentary rocks are folded and pushed up.

The folded, uplifted sedimentary rocks now form

lofty mountains, and volcanic activity often violent,

takes place.

NOTE: questions such as describe how the Himalayas, Rockies, Atlas, Andes, Alps were

formed. Such questions require similar information about the formation of Fold Mountains

with similar diagrams. The only difference is that the exact plates are supposed to be

mentioned in the explanation. For example, when explaining about how the Rockies were

formed, plates like Pacific and North America have to be mentioned.

State three characteristics of young fold mountains

i. They are associated with volcanoes and volcanic intrusions like Batholiths. This is

because the collision of plates makes magma to rise and form volcanoes or

solidify with the crust forming intrusive features.

ii. They are long and high as they were formed through orogenic movements of

plates.

iii. They contain rich minerals such as gold, tin, copper and petroleum.

iv. They are generally found on the western continental margins. This is because

such western margins are the ones which experience convergent boundaries

which contribute to the formation of Fold Mountains.

State three influences of young fold mountains

i. They often act as climatic barriers. Regions on one side of the mountain have

entirely different climate from that of the other side. For instance, to the west

of Rockies, in the coastland of British Columbia have mild winters, warm

summers and rain throughout the year while to the east of Rockies, the

Prairies have cold winters, hot summers and there is maximum rain in

summer. This is because of the Rockies which act as a barrier.

ii. They often receive heavy rains and or snow which may give rise to important

rivers. Such rivers may be used for irrigation and production of electricity.

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Examples of such rivers include Ganges in India for irrigation and Mississippi

in North America for electricity.

iii. Some contain minerals such as Copper, Gold, Tin in Bolivia. Such minerals

are mined and put into productive use.

iv. Are heavy forested and thus, they are sources of valuable timber resources.

For example, western Rockies which has coniferous soft woods and foothills

of Himalayas which have teak.

v. They act as barriers to transport and communication as it is difficult and

expensive to construct roads, railway lines, telephone links through them

NOTE: the above factors can also stand for the question which says “explain the effects of

the mountain building processes”

With the aid of well labeled diagrams, explain how Block mountains were formed

Block mountains were formed through both tensional and compression forces. A piece

of land is subjected to many faults or cracks. These are produced as a result of the

land being pulled apart. When this happens, two blocks on the sides goes downwards

leaving the middle block to remain behind. The middle block that stands up forms a

block mountain or horst. Below is a diagram

In this diagram, tensional forces pull the land

apart. Cracks develop on this piece of land

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The blocks subsides leaving one block to

remain and form a Block Mountain

Block Mountains are also produced through compression forces. In this, the land becomes

folded and cracks are produced. The blocks outside the cracks are pushed up and rise in a

reverse or thrust fault. The two blocks from Block Mountains later on the raised blocks may

be worn down through erosion. The diagram below shows this:

Compression forces acting on a piece of land

and cracks develop.

In this diagram, the blocks outside the faults

rise to form the Block mountains. It should be

noted that the gap formed creates a rift

valley. The sides of the blocks are then

subjected to erosion.

NOTE: this diagram also explains the formation of rift valleys by compression forces.

Give four examples of Block Mountains in the world.

- Vosges in Europe

- Hunsruck in Europe

- Block forest mountain in Europe

- Ruwenzori mountain (mountain of the moon) in East Africa

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What are the two characteristics of Block Mountains

i. The faulted side is very steep

ii. Usually long especially when formed along the rift valley

iii. The side facing away from the faulted side is generally less steep.

What do you understand by the term fault

This is the breaking of the earth’s crust ass a result of tensional and compression

forces

What is a fault

This is a break in the rocks produced by either tensional or compression force

Draw and label two types of faults

A fault is a break in the rocks of the crust. Faults are caused by either tensional or

compression forces. There are three main types of faults namely normal or dip- slip

faulty, reverse or thrust fault and shear or trans-current fault.

This is a normal fault. It is caused by

tensional forces. One block is pushed

downwards and is called a down throw

This is caused by compression force.

Rocks layers form one side is pushed

upwards.

Why is faulting important: give two reasons

i. Faulting permits ore-forming chemical solution to rise along fault planes.

ii. Faulting results into the formation of valleys. These form broad lowlands,

providing rich agricultural land, for example between Vosges and Black forest

block mountain.

iii. Situated along the faulting are hot springs which are utilized in healing

iv. Results into the formation of Block mountains of which apart from providing

rich agricultural soils, offer tourism to the areas, contain valuable timber for

furniture and help to bring rainfall to the areas whereby acting as source of

river.

What are the two negative influence of faulting

i. Fault scraps may form topographic barriers across which it is difficult to

build road s and railways

ii. As the earth’s crust is torn apart, faults are associated with volcanoes and

earth quakes which kill people and destroy property

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With the aid of a well labeled diagram, explain how the residual mountains were

formed.

These are mountains which were formed as a result of denudation processes. In this

over the years weaker parts of the earth are removed by agents of water, wind and

ice. The more resistant rocks or parts remai9n behind and stand out as a mountain.

The diagram below show how residual mountains were formed.

In the diagram the original level over 200

million years was at (a).

Due to the removal of less resistant rocks,

the level has been reduced to present level

leaving more resistant to stand as a

mountain

NOTE: residual mountains are also called Circum- denudation or circum- Erosion Mountains

Give three examples of Residual mountains

- Monadock in USA

- Scottish Highlands

- Scandinavian highlands

- Mulanje mountain in Malawi

- Zomba mountain in Malawi

- Vipya plateau in Malawi

NOTE: sometimes question will come in form of an example. For instance, describe how

Mulanje Mountain was formed.

Give three denudation processes which reduce the size of Block Mountains (6) (2001)

i. Weathering: this is the process whereby the block mountain is exposed to

weakening agents. It is being attacked and weakened and broken down due to

changes in temperature, roots of trees and rain water.

ii. Erosion: whereby the broken pieces are removed from the original place to

another different place

iii. Deposition in which the carried materials or sediments are left in another

area by the help of running water, wind and ice

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How is a mountain such as Fujiyama of Japan formed

Fujiyama is an example of a volcanic mountain. These mountains after the materials

ejected from fissures inside the earth’s surface solidify on the earth’s surface. These

materials include molten lava, volcanic bombs, cinders, ashes, dust and liquid mud.

These materials fall around the vent in successive layers, building up a volcanic cone.

Volcanic mountains such as Fujiyama are also called mountains of accumulation.

This is because they are formed due to the piling up of materials from the earth’s

crust on to the earth’s surface.

NOTE: when the question requires a diagram that of a volcano should be shown.

Give three other examples of volcanic mountains apart from Fujiyama in Japan

- Mount Mayon in Phillipines

- Mount Merapi in Sumatra

- Mount Agung in Bali

- Mount Hood in USA

- Mount Kilimanjaro in Tanzania

- Mount Kenya in Kenya

Give three characteristics of volcanic mountains such as Fuji in Japan

i. They are frequently of great height

ii. They are symmetrical in shape

iii. They are steep sided

iv. They tend to occur in isolated peaks

What are the two differences between Kilimanjaro and Ruwenzori mountains

i. Mount Kilimanjaro is a volcanic mountain formed through the accumulation

of material such as molten lava, volcanic bombs, cinder and ashes on to the

earth’s surface from the ground. This is not the same with mount Ruwenzori

which is a block mountain formed through the elevation of part of the earth’s

surface.

ii. Kilimanjaro is of great height while as Ruwenzori is generally long

What do you understand by the term diastrophism

This is the process which involves the folding and faulting of the lithosphere rocks

TYPE OF MOUNTAIN

PROCESSES INVOLVED

EXAMPLES

Fold mountains

A

Himalaya

B

denudation

C

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Block mountains

D

Ruwenzori

E

volcanicity

Kilimanjaro

A. Folding process

B. Residual mountain

C. Mulanje mountain

D. Tensional/compression

E. Volcanic

NOTE: the information above provides four types of mountains, the processes involved and

examples

VOLCANISM/ VOLCANICITY

What do you understand by the term volcanism

This refers to all various ways by which molten rock and gases are forced into the

earth’s crust and out on to its surface

What is the difference between magma and lava

Magma is the molten or semi-fluid materials formed through the melting of rocks

through high temperature and pressure while lava is when magma reaches the

surface, solidifies and loses its gases.

What are three characteristics of acid lavas

i. They are highly vicious with a high melting point

ii. They are light colored

iii. They have a high percentage of silica

iv. They flow slowly and seldom travel far before solidifying

v. They have steep sided cones

What the three characteristics of basic lavas

i. Are very hot about 1000

0

C

ii. They are highly fluid with a speed of 16-48Km/hr

iii. They are dark colored like basalt

iv. They flow quickly are very explosive

What are the effects of basic lavas

i. They affect extensive areas, spreading out as thin sheets over great

distances before they solidify

ii. The resultant volcano is gently sloping with a wide diameter and forms

flattened shield or dome

What are the effects of acid lavas

i. It results in land explosion, throwing out many volcanic bombs or

pyroclasts. This is because the accumulation of lava in the vent obstructs

the floe of the out pouring lava.

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ii. This is why these lavas are very violent. The lavas are so vicious that they

can form a spine or plug

iii. They form a cone which is steep sided.

Give two conditions that contributes to the formation of intrusive volcanic features

i. The strength of the rocks above the magma. When such rocks are hard

prevent magma form rising to the top.

ii. The pressure of magma if its very low, it cannot reach the top surface. This

makes it to cool and solidify within the crust.

With the aid of a well labeled diagram, describe the features formed by volcanic activity

when magma fails to reach the surface.

When magma fails to reach the surface it forms intrusive feature. Examples include

batholiths which is a very large mass of magma which accumulates in the crust

forming the root or core of a mountain. Batholiths are made up of granite and are

only exposed by the agents of denudation.

The other intrusive feature is laccoliths. This is a mass of magma which flat based

and dome shaped top fed by a pipe from a batholiths.

The dyke is another intrusive feature. This is a mass of magma that cuts across the

bedding planes. When they resist erosion, they stand up as a wall. Sometimes they

give rise to waterfalls.

A sill is another important intrusive feature. This is a feature formed when a sheet of

magma lies along a bedding plane. The diagram below shows intrusive features

formed by volcanism.

1. Batholiths

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2. laccoliths

3. Sill

4. Dyke

NOTE: A= lava flow is an extrusive feature

B= a volcano which is an extrusive feature

Explain the meaning of active, dormant and extinct volcanoes

- Active volcano is that volcano that erupts frequently or at least when they have

erupted within recent times

- Dormant volcano is a sleeping volcano that has been known to erupt and show

signs of possible eruption in future

- Extinct volcanoes are those that have not erupted at all in historic times but retain

the features of volcanoes.

Draw a large annotated diagram to show the structure of a typical volcano.

A volcano is a large cone shaped formed on the earth’s crust due to the

accumulation of materials from the ground. The following are the most important

parts of the volcano. A crater, a vent, pipe, dyke and layers of larva, ash or

cinders. The diagram below shows a volcano and its parts.

Explain how the volcano you have drawn is formed

It is formed when materials such as magma, volcanic bomb, cinders, ashes and

liquid mud collects in the magma chambers under the ground. Magma in this

chamber becomes under pressure and finds a way out through the cracks product

in the earth’s crust. Materials then escapes through the vent on to the earth’s

surface, building up a cone shaped mound which is called a volcano.

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How do an earth quake play part in the volcanic eruption

Earthquakes make the ground to shake. Such vibrations apart form just disturbing

the magma under the ground, they also make the earth to develop faults or cracks.

Such cracks act as passages through which magma moves on to the earth’s

surface and form cone shaped mounds called volcanoes.

List the different substances that are emitted during the eruption

- Volcanic bomb

- Cinders

- Ashes

- Dust

- Molten lava

- Gases

Give any two examples of volcanic features in Malawi

i. Hot springs at Mphizi- Chiweta in Rumphi district. These show that rocks

are heated by the interior forces like magma which in turn heat up water

that moves out inform of a river

ii. Mulanje Mountain has a trace of igneous intrusions especially around the

area where bauxite has been prospected. Igneous are rocks formed

through volcanicity.

Name one major region which has active volcanoes.

The circum- pacific ring of fire, an area encircling the Pacific ocean with a lot

of volcanoes and earthquakes.

Explain three constructive effects of volcanoes

i. Some lava outpourings have weathered to give rise to fertile soils which

are of agricultural value. For example, the western part of the Deccan

plateaus in India, the plains around Etna.

ii. Volcanic activity sometimes results in the formation of precious stones and

materials. For example, Diamonds of Kimberly, Copper deposits of

Sudbury in Canada.

iii. Source geo –thermal power. Some hot springs are utilized for heating and

supply of hot water to buildings in New Zealand and Iceland.

iv. It also enhances tourism because volcanoes give rise to scenic features of

great beauty

Explain two destructive effects of volcanism

i. Some eruptions cause loss of life. For example that of Krakatau, Mount

Pelee where over 20,000 people were killed

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ii. Some eruption cause great damage to property burying them with ashes.

Infrastructure such as bridges, roads, cities are buried in ashes and

destroyed. For example the Vesuvius which buried Herculaneum and

Pompeii cities with ash.

Why is rescue work generally so difficult following a volcanic eruption

Some volcanic eruption contains basic lava which is highly fluid. This makes the

lava to move very fast and cover large areas. In addition, some eruption is

accompanied by lots of force which give rise to earthquakes. These further destroy

a lot of property especially buildings that fall down.

Suggest two reasons for the frequency of earth quakes and tremors in areas associated

with volcanic activity (2002)

i. Volcanic eruption break rocks in the earth’s crust. The

displacement of such rocks after being broken cause the ground to

shake hence earthquakes and tremors.

ii. Volcanic eruption is accompanied by a lot of force. This is

generated when materials from the ground move out. This force

makes the ground to shake thereby producing earthquakes and

tremors.

Explain the precautionary measures you would suggest for people living in areas

associated with volcanic activity (2002)

i. Following the historical information about the occurrence of volcanoes in

the area. When the historical map shows that the volcano is about to

happen, people should move out of the area

ii. Measuring the occurrence of earthquakes. Earthquakes can indicate the

occurrence of a volcano

iii. Keeping building materials, food stuffs in storage so as for them to be used

as soon as a volcano occurs.

iv. Listening to weather forecast. When there is a possibility of a volcano,

people to move out of the area

Describe how Caldera lakes are formed (2005)

These lakes are formed on top of a volcano after a volcanic eruption; the mouth of

a volcano called a crater is blown off by the last flowing magma. This creates a

large depression an top of a volcano called a Caldera. Water then collects on this

part and forms a lake called a Caldera. The diagram below shows this

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1. Study the figure below of the world map, showing volcanic areas and larva

plateau and answer the questions that follow (1193) (2000) (1975)

a. Name the lava plateau marked A-J

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A. Columbian and

snake river

plateau

B. Parana lava

plateau

C. Patagonian lava

plateau

D. Icelandic lava

plateau

E. Ethiopian

highlands

F. Drakensburg

G. Siberian plateau

H. Deccan plateau

I. Mongolian

plateau

J. Kimberley plateau

b. Name the volcanic mountains marked 1-6

1. Mauna Loa

2. Cotopaxi

3. Vesuvius

4. Kilimanjaro

5. Krakatau

6. Fujiyama or

Fuji

7. Pelee

8. Popocatepetl

9. Etna

10. Mt. St.

Helens

11. Helga fell

(Iceland)

Name the fold mountains marked P, Q, R, S and T

P= Rockies

Q= Andes

R= Alps

S= Atlas

T= Himalayas

Account for the distribution of volcanoes, earthquakes and fold mountains on the map

above.

Fold mountains were formed within the earthquake and volcanic zones in the so

called the pacific ring of fire as the map shows. This happens because the

formation of Fold Mountains, volcanoes and earthquakes are associated with

plate boundaries. All these features are found in the same area as they follow

plate boundaries. In such plate boundaries there is the movement of the crust

which eventually contributes to the formation of Fold Mountains, volcanoes and

earthquakes.

The picture below shows geologic activity taking place. Study it and answer the question

that follows (1990)

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What activity is taking place in the photograph

This is volcanic eruption or volcanicity\

Name three areas, one in Africa, Europe and America, experiencing this activity.

Africa= Kilimanjaro in Tanzania

Europe= Vesuvius around the Mediterranean sea

America= Rockies in North America

Describe the formation of the landform shown in the picture (describe how a volcano is

formed pages behind)

Explain three benefits and one disadvantages of occurrence of the landform shown in

the picture for human life and settlement

(Constructive and destructive effects of volcanism)

EARTHQUAKES

What do the following terms mean

i. Earthquake

This is the sudden earth movements or vibrations in the earth’s crust

ii. Focus

This is the point at which an earthquake originates under the ground

iii. Epicenter

It is the point on the earth’s surface immediately above the focus. It is a place

where the shock waves first hit the surface.

Describe two causes of earth quakes

i. Volcanic eruptions in which the movement of molten rock below or on the

earth’s crusts which intern is caused by the movements of tectonic plates

ii. Converging movement of tectonic plates which generate a lot of force that

cause the ground to shake

iii. One tectonic plate sliding over or past another plate along the line of fault.

Suggest why the “pacific ring of fire” is so called?

This is an area full of volcanoes and earthquakes encircling the Pacific ocean,

especially in plate boundaries.

Mention three main areas where the majority of earthquakes occur

i. The mid oceanic ridges

ii. Oceanic deeps and volcanic islands

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iii. The regions of crustal compression

Explain briefly for the occurrence of earth quakes in the above named areas

These places are in the plate margins. In such places, the movement of plate occurs.

Such movements of plates trigger vibrations which are called earthquakes.

Describe three effects of earthquakes (2005) (6)

i. They cause tidal waves called tsunami. These break the coastal areas

destroying people and property as they originate from oceans.

ii. They cause landslides which bury people’s property an infrastructure such as

bridges, roads and railways with sand.

iii. They cause vertical and lateral displacement of parts of the crust.

iv. Cause fires which destroy cities.

Copy out and complete the following paragraph using the word supplied in the list

below:-

Earthquakes occur when two A try to move past each other in different directions.

This normally occurs at a B or a C plate boundary. The rocks are put under a grea deal

of D and start to E. eventually, when the stress is too great, the rocks suddenly break

along a F. energy in the form of G H radiates out in all directions, causing the ground

to I.

Bend, shake, seismic waves, slipping, fault line, plate, destructive

A. Plate

B. Slipping

C. Destructive

D. Stress

E. Bend

F. Fault line

G. Seismic

H. Waves

I. Shake

In earth quakes what are the uses of the following:-

i. Seismograph

An instrument which measures the intensity o an earthquake, through

recording its vibrations

ii. Richter scale

Used for measuring the total amount of energy released by an earthquake.

What do you understand by the following in connection with earthquakes:-

i. Seismic waves

These are vibrations produced by an earthquake which cause destruction as

they radiate outwards from the epicenter

ii. Magnitude

This refers to the total amount of energy released by an earthquake which in

turn is measured by using a Richter scale.

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What is the difference between primary effects and secondary effects of an earthquake

Primary effects are the immediate damage caused by an earthquake where as

secondary effects are often effects of the earthquakes

Give two examples of primary effects of earthquakes

i. Collapsing of buildings such as houses

ii. Destruction of roads

iii. Destruction of bridges

Give two examples of secondary effects of an earthquake

i. Causes fire as earthquakes destroy gas pipes and electric cables causing fire

to spread. This fire may destroy cities.

ii. Cause tidal waves known as tsunami these usually happen when an

earthquake has its focus in seas and oceans. These huge tidal waves destroy

houses close to the sea and ships at anchor. For example on 26

th

December

2004, a tsunami happened across Asian countries of Indonesia, India, and

China leaving many people homeless while 300,000 died.

iii. Landslides especially in steep river- valleys and areas of weak sand and clays.

In 1970 an earth quake of magnitude 7.8 in Peru caused a huge landslide high

in the Andes Mountains which killed 20,000 people.

iv. Diseases and famine. Fresh water supplies are often cut off due to burst water

pipes. Typhoid fever and cholera can spread easily, especially in large cities

cut off from medical supplies by damaged communications.

Why are earthquakes likely to be more dangerous in less developed (LDC) countries

than developed countries like Japan

i. Many less developed countries cannot afford early warning systems or

evacuation plans than developed countries

ii. Houses in many developed countries are built up with strong structures than

can withstand earthquakes. In less developed countries, the houses are made

up of poor structures that are easily destroyed

iii. Relief after an earthquake in less developed countries is a problem. Basic

necessities such as food, clothes, medicine become a problem to less

developed countries is not a problem.

What is it that earthquakes cause a lot of destruction in more populated area such as

cities

i. Houses are close together with power lines that apart from destruction to the

buildings, fir can easily spread and difficult to be extinguished

ii. Diseases are spread more quickly in more populated areas.

ROCKS

Define the term rock

It refers to any naturally formed aggregate of mineral particles whether hard or

soft.

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Give three important minerals that rocks contain

i. Quartz which is sometimes called Silica. this is a compound of Silicon and

oxygen and is a very common mineral

ii. Felspars which are compounds of Potassium, sodium, calcium

iii. Micas which are compounds of Potassium, magnesium, silicon and

aluminum.

Explain how the following groups of rocks were formed, and for each group give at least

two examples (1996) (1986) (2001)

i. Sedimentary rocks

These are rocks which were formed through the collection of sediments.

They are formed through the collection of clastic sediments, non clastic

sediments and organic sediments when transported, deposited, compacted

and lithified. Examples of sedimentary rocks are conglomerate, Breccias,

sandstone, shale, Limestone

ii. Igneous rocks

These are rocks formed through the cooling and solidification of molten

material called magma. Those formed after magma solidifies and cools on

the earth’s surface are called volcanic or extrusive while those formed

within the earth’s crust are called intrusive.

Examples include granite, diorite, gabbro, basalt, andesine, peridotite,

punice and scoria.

iii. Metamorphic rocks

These are rocks which are originally igneous or sedimentary but have

changed into character and appearance due to application of intense heat,

pressure, water and air.

Examples include: slate, schist, phyllite, gneiss, quartzite and serpentine.

Mention three characteristics of each group of rocks motioned above

i. Characteristics of sedimentary rocks:

- They occur in layers, that is, they are stratified

- They contain fossils, that is , they are fossilized

- They are non-crystalline, that is, they do not contain crystals

- They are generally soft rocks.

ii. Characteristics of igneous rocks

- They are crystalline in nature, that is, they form crystals

- They are not stratified thus they do not occur in layers

- The rocks are non fossiferous, that is, they do not contain fossils

iii. Characteristics of metamorphic rocks

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- They do not contain fossils

- They are generally very hard rocks

- Minerals are arranged in bands of layers in a process called foliation

Which group of rocks mentioned above:-

i. Is not stratified, and why

Igneous rocks because these rocks are formed through the cooling and

solidification of magma which takes place almost within the same time,

making them not to form layers.

ii. Contain fossils, and how

Sedimentary rocks because the fossils are carried together with the

sediments during transportation. When such sediments are deposited by

the action of wind, water and ice, fossils of plants and animals are

deposited together, compacted and lithified together with sediments. This

makes remains of plants and animals to appear in the sedimentary rocks.

what difference can be noticed in terms of crystals between Gabbro and Basalt

Gabbro would develop large crystals while basalt would develop small crystals

Give a reason for your answer in (b)

Gabbro cools and solidifies within the earth’s crust. This makes cooling to take place

very slowly, which result into large crystals to develop as crystals have a lot of time to

grow into large ones. Basalt solidifies on the earth’s surface where cooling takes

place very fast. This fast cooling result into small crystals because the crystals are

deprived of enough time to grow into large ones.

What determines the size of the mineral grains of an igneous rock

It is determined by the rate at which cooling takes place. Fast cooling produces small

crystals while slow cooling produces large crystals.

with the use of a flow diagram show how igneous rocks were formed

Igneous rocks are those formed through the cooling and solidification of magma. The

flow diagram below shows this:-

Explain the role played by the following in the formation of metamorphic rocks

i. Heat: this causes the minerals to recrystalise

ii. Pressure: this changes or alters the rock structure

iii. Water: dissolves some rock minerals and deposits other minerals thereby

changing the composition of the rock

MAGMA

COOLING

SOLIDIFICATION

M

IGNEOUS ROCKS

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iv. Air: Move through the pores and come into contact with different rock

elements changing its composition

put each of the following rocks into the appropriate classes

i. Conglomerate = sedimentary rock

ii. Gneiss = metamorphic rock

iii. Marble = metamorphic rock

iv. Scoria = extrusive igneous rock

v. Shale = sedimentary rock

vi. Gabbro = intrusive igneous rock

vii. Serpentine = metamorphic rock

viii. Siltstone = sedimentary rock

what happens to the following rocks when they have been metamorphosed

a. limestone = changes to a metamorphic rock called marble

b. granite = changes to a metamorphic rock Gneiss

c. Conglomerate = changes to a metamorphic rock Gneiss

d. Shale = changes to a metamorphic rock called slate or phyllite

e. Siltstone = changes to a metamorphic rock called Schist, or slate or phyllite

f. Basalt = changes to a metamorphic rock called serpentine

g. Sandstone = changes to a metamorphic rock called Quartzite

Describe how sedimentary rocks are chemically formed, with the help of at least two

examples

These are sedimentary rocks formed through the precipitation of minerals, which

were dissolved in water. With the help of evaporation of water especially in shallow

seas, minerals remain behind, collect, compacts and lithify to form chemically

sedimentary rocks

Examples of chemically formed include:

- Borax

- Potash

- Gypsum

- Nitrate

- Certain limestone

- Rock salt

Explain how organically sedimentary rocks were formed with atleats two examples

These are rocks formed from the remains of plants and animals. Those formed

from the remains of plants are called carbonaceous while those formed from the

remains of animal are called calcareous

Examples of such rocks are:

i. chalk formed from

animals

ii. coral formed from

animals

iii. peat formed from plants

iv. coal formed from plants

v. lignite formed form

plants

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With the help of a flow diagram, explain mechanical sedimentary rocks were formed

These are rocks formed through the collection of clastic sediments. This kind of

sedimentary rocks are formed from the existing rocks, which are exposed to

weathering agents where the break into small particles called the sediments. The

sediments are then transported by water, wind, and ice. The sediments are then

deposited in geosynclines, which are seas and oceans bordering the continents.

The sediments in the geosynclines are compacted or cemented together. The

sediments are then lithified in which water and heat help to bake the sediments to

turn into sedimentary rocks. The flow diagram below shows this:

Examples of mechanically sedimentary rocks are

- conglomerate

- Breccias

- Sandstone

- Shale

- Siltstone

- Loess

- Maraine

- Mudstone

- Clay

describe the ways in which a sediment can turn into a hard sedimentary rock

(as above)

Explain the following terms in the study of rocks:

a. Metamorphism: - the process through which other rocks whether

sedimentary or igneous turn into metamorphic rocks through the application

of intense heat, pressure, water and air.

EXISTING

ROCKS

WEATHERING

TRANSPORTATION BY

WIND, WATER

GLACIERS

DEPOSITION IN

A GEOSYNCLINE

COMPACTION

LITHIFICATION

SEDIMENTARY

ROCKS

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b. Metasomatism:- this is the type of metamorphism by which gases play

important role of entering the pores of a rock and change it to a metamorphic

rock

c. Foliation:- this is a term given to all metamorphism in metamorphic rocks

d. Metasediment:- this is a term given to all metamorphic rocks derived from

sedimentary rocks

e. Dynamic metamorphism:- the term given to the type of metamorphism in

which pressure plays a great role

f. Thermo or contact metamorphism: - the type of metamorphism in which

heat plays important role to change the rocks into metamorphic.

g. Regional metamorphism:- the type of metamorphism that combines heat and

pressure and operates over a very large area

h. Hydrogenic rocks:- these are rocks which are formed in water especially

sedimentary rocks

i. Stratification: The terms given to the arrangement of layers in sedimentary

rocks, this appears to be in form of lines. This happens because the layers are

arranged in different times under different environments with different sizes of

sediments.

With the aid of a diagram describe the rock cycle

The rock cycle describes the change of a rock from one kind to another under

different conditions. Changes that take place beneath the earth’s surface are due

to high temperature and pressure, while on the surface, weathering is the most

important. Sedimentary rocks if burned under the ground melt due to high

temperature and pressure, and turn to igneous rocks often cooling. These igneous

rocks are subjected to further heat, pressure and water change to metamorphic

rocks. The metamorphic rocks can be uplifted and weathered to form sediments,

which later form sedimentary rocks.

Sedimentary Rocks

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Igneous Rocks Metamorphic Rocks

NOTE: With a diagram, describe how granite rock can be turned into slate and later

sandstone (this question requires the knowledge of the rock cycle)

Study the rock cycle below and answer the questions that follow

C B

F

A

D

E

1. what is the importance of stages:

a. X= it forms magma which acts as a raw material in the formation of igneous

rocks through cooling and solidification

b. Y = provides small particles known as sediments which when deposited,

compacted and lithified forms sedimentary rocks.

2. what is the processes that take place in stages

A = weathering

SEDIMENTA

RY ROCKS

Y

IGNEOUS

ROCKS

X

METAMORPHIC

ROCK

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B = transportation, deposition, compaction and lithification

C = intense heat, great pressure, water and air

D = melting

E = cooling and solidification

F = melting, cooling and solidication

Explain two roles played by wind, water and ice in the formation of sedimentary rocks

1. in weathering process, these helps to weaken the rocks which are then broken

into small particles known as sediments

2. These agents help to transport the sediments to an area where they are

deposited. In this deposition area in geosynclines is where compaction and

lithification take place in order to form sedimentary rocks

Mention two economic importance of rocks (2008) (2001) (1993) (1996) (1986)

a. Rocks weather to give fertile soils which are used for the cultivation of crops, for

example tea on the foot of Mulanje mountain

b. clay, a sedimentary rock is used in brick making

c. Limestone, a sedimentary rock is used in the production of cement. In Malawi

limestone is found at Balaka as the deposits at Changalume are depleted

d. Coal, a sedimentary rock is used in thermal power production. Coal in Malawi is

mined at Mchenga coal Mine in Rumphi district

e. Some rocks contain aquifers, which store water. Boreholes are then sunk to get

this water to be used

f. Rocks such as gravel are used in the construction of certain crops e.g. potash,

Gypsum, nitrates and Borax.

give two reasons why igneous rocks do not contain fossils

g. As the rocks are formed through the cooling and solidification of magma, the

fossils are burnt during the melting process.

h. Such rocks are formed far below the crust where fossils cannot be found

Why are fossils likely to be found in Shale and sandstone and not granite

Shale and sandstone are sedimentary rocks formed through the collection of

sediments. Such rocks are likely to have fossils because during the transportation

of sediments by the action of water and wind, fossils are transported together. The

fossils are then deposited with sedimentary rocks. Granite as an igneous rock was

formed through the melting, cooling and solidification of magma. In this process,

the rock cannot contain fossils because the fossils are burnt up with the great

heat.

Page 40 of 159

THE HYDROSPHERE

Define the term hydrosphere (2006)

This is part of the earth, which is composed of water masses such as lakes, rivers,

oceans, seas and dams.

NOTE: The hydrosphere covers about 70% of the earth’s surface

Draw a clearly labeled diagram to illustrate the hydrological cycle (1993) (1986) (1997)

(2002) (2007)

The hydrological cycle refers to an endless circulation of water between the earth’s

surface and the atmosphere. The system includes processes such as evaporation,

transportation, condensation and capillary attraction. The diagram below shows

this:-

1. Describe how the hydrological cycle that you have drawn works 919986)

(1997) (1998) (2005)

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The hydrological cycle starts with the presence of solar energy. This makes water

to evaporate on both land and water masses. It also makes vegetation to lose

water in form of vapor in a process called transpiration. The combined loss of

vapor from both vegetation and land and water masses is referred to as evapo-

transpiration.

Water vapor in the atmosphere loses its temperature as temperature decreases

with altitude, and become cooled. The vapor then cools below its dew point which

is also known as adiabatically cooling. Tiny droplets then start to form in a

process called condensation.

The tiny droplets then combine to form clouds. The clouds become very heavy to

float in the atmosphere and fall to the ground through the process called

precipitation. This precipitation takes the forms of rain, fog, snow, hail, drizzle

and sleet.

On the earth’s surface, two processes take place namely infiltration and runoff.

Infiltration is the process whereby water soaks into the soil. Runoff is the water

that flows on the earth’s surface joining lakes, rivers. This water then evaporates

into the atmosphere.

Water that soaks into the ground move side ways in a horizontal in a process

called percolation to join the ground water. This underground water through

capillary attraction is absorbed by roots of trees and eventually transpires to

complete the circulation and restarting the hydrological cycle.

NOTE: The underlined words are the main features of the water cycle, which must be

present in the explanation

Dew or morning mist is not a form of precipitation because it forms on the earth’s

surface following a decrease in temperature towards sunset as vapor fails to rise up

into the atmosphere.

Give three reasons why it is important to maintain the hydrological cycle (1997) (1993)

a. water is used for domestic and industrial services

b. it serves as habitat for aquatic animals such as fish, hippos and crocodiles

c. lakes and rivers are often popular tourist attraction centre because water

is a source of natural beauty of the environment

d. water stored in dams is used to produce hydroelectric power

e. it provides a means of communication by ship or boat

f. water is the basis for the sporting activities such as swimming and skiing

Explain human activities that can disturb the hydrological cycle

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a. Air pollution through the release of nitrous carbon dioxide and

chlorofluorocarbons. These attack the ozone layer making it to have holes.

The result is that ultraviolet rays from the sun such as gamma rays, x-rays and

infrared move to the earth’s surface causing global warming. This global

warming tampers with the hydrological cycle in the sense that it affects

rainfall pattern resulting in heavy rains or no rains in others.

b. Through the wanton cutting down of trees without replacing them which is

called deforestation. When trees are cut down, the rate of transpiration is

relatively reduced. This brings about the shortage of water vapor that forms

very small clouds. The result is that there is little rain throughout as the rate

of transpiration is reduced.

c. Application of chemicals in water bodies such as rivers, lakes, oceans and

seas. This slows down the rate of evaporation inefficient. Small clouds are

formed and this brings little rainfall.

d. Poor farming practices, also disturbs the water cycle. Examples of such

practices are cultivating along steep slopes, overstocking, overgrazing and

setting bush fires. These apart from reducing vegetation, encourage erosion,

which have negative impact on the circulation of water within the

hydrological cycle as a system.

e. The acid rain also disturbs the water cycle. Acids, which remain in the air, are

carried by rain to the ground. The acid rain destroys the leaves of the

vegetation hence transpiration rate is affected negatively as the number of

stomata decreases.

Suggest problems that are likely to be faced by nations as a result of the disturbance of

the hydrological cycle

g. Drought conditions, making crops to wilt and dry up. This brings famine

h. Heavy rainfall which results into flooding that destroys fields, homes and

causes extensive erosion of fertile soils

i. Many waterborne diseases caused by bacteria or parasites living in water

because of untimely rains.

j. The little available water can be polluted by people resulting into outbreak

of many diseases such as cholera

Suggest three ways in which the hydrological cycle can be maintained

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k. By practicing afforestation and reforestation. This helps to maintain the

water cycle in that the planted trees increase the rate of transpiration. This

makes a lot of water vapor to be present in the atmosphere forming heavy

clouds, eventually heavy rainfall results.

l. Avoidance of use of devices that release dangerous gases called

chlorofluorocarbons (CFCs) into the atmosphere. This will make the

ozone layer to be maintained which in turn prevents strong rays such as

gamma rays, x rays and infra red from reaching the earth’s surface and

cause global warming. This will reverse the unusual distribution of

rainfall and bring back the usual one.

m. Avoidance of use of emissions of various elements or compounds into the

atmosphere such as carbon dioxide, Sulphur and nitrogen when such are

avoided, chemical reactions that bring acid rain will not take place.

n. Use of good farming methods, which ensures full protection of vegetation

from destruction. This will make a lot of vapor to be released through this

vegetation.

o. Conservation of water catchments areas. When water catchments areas

are conserved, the rate of evaporation from those water masses is

increased, thus will in turn also increase the number of tiny water droplets

that will form. The result will be a big and heavy cloud, which will bring

heavy rain.

p. Weather forecasting. Listening to weather bulletin if there is a possibility

of heavy rainfall, then to be prepared for measures that can reduce

flooding of water if there will drought conditions, planting crops, which

are drought resistant.

Give three examples of natural resources which should be maintained in order to

maintain the water cycle

q. Water which when evaporates or is absorbed by trees turns into vapor that

form clouds and come down as rain.

r. Vegetation: apart from protecting the soil, it transpires and adds vapor to

the atmosphere contributing to the formation of clouds.

s. Soil, which supports vegetation

OCEAN CURRENTS

What is the difference between an ocean current and a drift

an ocean current is a large mass of surface water that circulates in regular

patterns around the oceans while as a drift is an ocean current that is primarily

caused by the prevailing winds.

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Why are some ocean currents warm and others cold

This happens because of the difference in the originality. Warm ocean currents

are those regions with higher temperatures while as Cold Ocean currents are

those that flow from towards equatorial regions.

How are ocean currents caused by the following factors:

a. Temperature

The temperature in the equatorial regions is higher while that of the Polar

Regions is lower. Warm equatorial water move slowly along the surface pole

wards while the heavier cold waters of the Polar Regions creep slowly along the

bottom of the sea equator wards. This type of movement creates friction that

causes an ocean current as warm water moves on top of cold water.

b. planetary winds

When planetary winds blow over the ocean, surface water is pushed in one

direction creating a regular pattern of movement of large masses of water around

the ocean.

c. . Rotation of the Earth

When the earth is rotating, it creates a force known as a coriolis force, which

pushes surface water of an ocean in one direction and this creating an ocean

current.

d. Salinity

Water of high salinity that is with high concentration of salts is denser as

compared to water of low salinity, which is lighter. Therefore, water of high

salinity will sink because it is denser while that of low salinity will move on top of

high saline water because it is lighter. This type of movement creates frictions that

eventually trigger an ocean current.

Study the diagram below which shows ocean current patterns and answer the questions

that follow:

Surface circulation Sea Level

A B

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What name is given to the circulation marked A and B

A= Gyrotic circulation

B= Convective ocean current circulation

State two causes of pattern A

i. prevailing winds

ii. earth rotation

State two causes of pattern B

a. temperature

b. salinity

Study the map of the world below which shows location of ocean currents and answer

the questions that follow (1990) (1997)

1. Name the ocean currents marked A, B, H, D, F

A= west Australian current

B= Kuro Siwo current

D= North Pacific current

H= Benguela current

F= Canaries

What impact does each of the following currents have:-

1. current G

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- as a warm current it brings heavy rainfall to the coastal area after picking up

moisture from the oceans

- it also encourages fishing along the coast of Uruguay and Argentina

2. The meeting of current C and B in the area

- Since C is a cold ocean current while B is a warm current. The meeting of the two

creates a major fishing ground. This happens because when these two meet, there

is precipitation of minerals which facilitates the growth of micro-scopic plants

called planktons which are food for fish

- The meeting of the two creates fogs which impeded visibility and can consequently

lead to loss and capsizing of ships

What is the cause of the upwelling of water in the areas shaded on the map

The movement of cold ocean currents causes this from the Polar Regions. When such

ocean currents move from the Polar Regions, they creep under the surface since they

are denser. As such, currents approach the tropical regions; they become heated and

start going up from the bottom as they lose density. This is exactly that makes water to

up well as the currents appear on the surface waters.

Why does ocean current F change direction seasonally

This happens due to the apparent movement of the sun that brings about differences in

terms of pressure that in turn drives the current towards a certain direction. For

example, in June the sun appears to be overhead in the northern part, which then

attains a low pressure. The current then move from the southern part which is a high

pressure area to the northern part. In the month of December, the sun appears to be

overhead in the southern part. This makes the southern [art to develop a low

pressure. The current then changes direction from the north to the south as the north

develops a high-pressure area.

Explain four factors that influence the direction of ocean currents as shown on the map

above (1990) (1997)

- The shape of continents: Landmasses obstruct and divert a current. For example,

the shape of the southern Chile makes the Peruvian current to flow following the

land coast going northwards.

- Rotation of the earth: This makes ocean currents to deflect to the right in the

northern hemisphere and to the left in the southern hemisphere from their normal

courses. For example, the Mozambique warm ocean current deflects to the left

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encircling Madagasca as a result of the earth’s rotation which brings coriolis

force into effect.

- Wind direction: The direction taken by the planetary winds is the same direction

taken by an ocean current in that particular area. For example, the flow of the

north Atlantic drift follows the planetary winds

- Temperature also influences the direction of an ocean current. Equatorial regions

have a high temperature while polar areas have low temperatures. Warm ocean

currents flow towards the Polar Regions as it is a warm current while as canaries

flow from the Polar Regions towards the equator as it is a cold ocean current.

Examine with specific examples two negative effects of ocean currents (1997)

a. Cold ocean current from Polar Regions distribute coldness to the

tropics influencing a particular type of climate. For example, the coast

of Namibia where fogs are common.

b. Cold ocean currents do not bring rainfall to the neighboring

landmasses. This is because they do not absorb moisture. This makes

them to be responsible for the existence of deserts. For example, the

canaries are responsible for the formation of the Sahara desert, the

Benguela for the Kalahari Desert, Peruvian for the Atacama desert.

c. On shipping the currents have two negative effects:

a) Ocean currents increase the height of tides and can make ship loading

and off-loading difficult, not to mention about capsizing and loss of

goods.

b) The meeting of cold and warm ocean currents creates fogs that

impedes visibility and can consequently lead to loss and capsizing of

ships. Examples of such areas include the new Founder land where the

Labrador tend to meet the North Atlantic drift, off the coast of Japan

where the Kamchatika meets the Kurosiwo.

Explain any two beneficial effects of ocean currents on human activities (2006)

a. Warm ocean currents distribute heat from the tropics to the poles. This

help to melt ice thereby making some ports to be used throughout the year

as they are ice-free. For example, the Vancouver port is ice free in winter

because of the North-Pacific warm ocean current.

b. On climate, warm ocean currents bring rains to the coastal areas. This is

because they are able to pick up moisture over the oceans and bring heavy

rainfall to the coastland. For example, the Mozambique warm oceans

current bring rainfall to the coast of East Africa.

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c. On fishing, the meeting of the cold and warm ocean currents creates major

fishing grounds. This happens because such a meeting encourages the

precipitation of minerals that facilitate the growth of micro- scopic plants

called planktons, which are food for fish. For instance, the western Pacific

grounds where the Kamchatika meets Kurosiwo, the Northwestern Atlantic

where the Labrador and North Atlantic Drift creates the fishing ground.

d. On shipping, ships soil following the direction of currents as they flow

hence easing their movements, less fuel which reduces expenses and

transit time.

Name two warm ocean currents of the North Atlantic and any two cold ocean currents

of the North Pacific

e. Warm ocean currents of North Atlantic

 Gulf stream

 North Atlantic drift

f. Cold ocean currents of North Pacific

 Californian cold current

 Kamchatka cold current

On the map provided above shade and name two areas, which are usually foggy for

most of the year.

Shade the areas where a warm ocean current meets with a cold ocean current.

Examples of such areas:

g. Off the coast of New Founder land where the Labrador and east Tronland

meets the North Atlantic Drift

h. North West Pacific, off the coast of Japan where the Kamchatka meets

Kurosiwo

i. North east pacific where the North Pacific warm ocean current meets the

Californian cold Ocean current

Study the figure below, which shows part of the world and ocean currents

Diagram

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3. What aspect of weather is likely to develop in the area marked A

Fogs are likely to develop in the area. This is because there is the meeting of Gulf

Stream that is a warm currents and the esast Green land which is a cold current.

The westerly winds carry warm air from the Gulf stream when then meets the cold

air from the east Greenland.

4. State two beneficial effects of the cold ocean currents

a. As they creep under the water surfaces from the polar region, when

approaching the tropics, they up well. This help in the development of

fishing grounds because they help to stir up minerals for planktons.

b. Help to reduce the high tropical temperatures especially in summer

Study the figure below which shows a map of southern Africa showing cloud cover and

answer

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5. Describe the variations in cloud cover in the region

The eastern part of southern Africa contain rain bringing clouds while as the

western part of the Southern Africa contain fine weather clouds.

6. Suggest why there are these variations

i. A warm ocean current influences the eastern part. Being a warm current,

it brings heavy rainfall to the coastal areas. This is in contrast with the

western coast, which is under the influence of a cold current. This does not

bring a lot of rainfall to the area, hence fine weather clouds.

ii. The existence of the Drakensberg Mountain acts as a barrier. The rain

that is brought by the warm current, very little can reach the western part

as the area appears to be in the rain shadow area due to the existence of

the mountains.

7. With aid of a diagram, explain how ocean currents are caused by

temperature variations between polar regions and tropics (see convective

circulation)

8. Nain and Glasgow are on the same latitude of 56

0

N. explain with the aid of a

large sketch map, why Nain has a lower mean January temperature of -

21.6

0

C while Glasgow has 3.9

0

C (14) (1996)

Nain is in North America while Glasgow is in Britain which is an island in the

Atlantic Ocean. Since these lie in the same latitude of 56

0

N, are supposed to have

almost the same temperature on average. There must be a factor that brings about

the differences in temperatures. This is what the work below will explain.

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According to the sketch above, both towns really lie within the same latitude 56

0

N.

The town of Nain has a lower temperature of -21

0

C because it is under the

influence of the Labrador cold current. Being a cold current, with the low

temperatures obtained from the Polar Regions, the current lowers the temperature

of Nain. The situation with Glasgow is different. The town is influenced by the

North Atlantic Drift warm ocean current. Being a warm ocean current, it helps to

raise the temperature of the town with the tropical heat hence 3.9

0

C.

ATMOSPHERIC PRESSURE

what is air pressure

This is the force exerted by the atmospheric air on the earth’s surface.

Define the term pressure gradient

This mean the rate at which the atmospheric pressure changes horizontally in

a certain direction on the earth’s surface

In a pressure gradient explain what it means when:

a. The isobars are close together

It means the gradient is steep and air is quickly drained that is, the movement

of wind is very great or fast.

b. The isobars are far apart

It means the gradient is slight and wind speed is low

With the help of a diagram, explain the effect of volume on air pressure

When the volume is small, air pressure increases. This is because air

molecules are concentrated in a small space. This makes the air molecules to

push out with a lot of force which in turn increases pressure. Conversely,

when the volume is increased, air pressure becomes low. This is because the

space becomes large and air molecules have a lot of room. This makes them to

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push out with less force which in turn lowers the pressure. The diagram below

shows this

Same amount of air

Large space small space

Low pressure High pressure

Explain why:

a. The air pressure is higher at higher latitudes than at low

latitudes

High latitudes are those that are from the temperate regions to the

Polar Regions especially along 90

0

North or South of the equator.

Low latitudes are those that are closer to the equator especially

within the tropics. Air pressure is higher at high latitudes because

the temperature in such areas is very low as the sun appears to be

very far from them. This low temperature makes air to be

concentrated in a small area as it contracts. This makes it to push

out with a lot of force. Pressure at low latitudes is low because such

places experiences high temperature. This heats up the air which

then rises and occupies large volume. This in turn reduces pressure

as the molecules cannot push out with a lot of force.

b. The air pressure is generally low at high attitudes than at low

altitudes

Altitude is the height above the same level. High altitude areas are

those like on top of mountains while low altitude areas are like those

along the sea level. Air pressure is low at high altitude like on top of

mountains because in such places there are few columns of air. This

makes air to push out with little force thereby lowering the pressure.

The air pressure is generally high at low altitude areas like along the

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sea level because such places support many columns of air. If the

columns of air are many, it makes air to push out with a lot of force.

This in turn increases air pressure.

c. The same quantity of air exerted different in different volume

Small volume makes the air to be concentrated in a small are. This

makes it to push out with a lot of force which in turn increases air

pressure. Large volume makes air molecules to be spread far apart.

This makes it to push out with little force and the pressure is

reduced. Same quantity of air exe4rted differently, when the volume

changes.

Explain why:

a. There is low pressure along the equator

This is due to temperature. As the temperature is high along the equator, it

makes air to be heated up and rise. When this happens, the air occupies a

large volume which makes pressure to be low as the air pushes out with little

force.

b. There is high pressure along the latitudes

Horse latitudes are those 30

0

North or South of the equator. These areas have

high pressure because the air that escapes from the equator as a result of

temperature crosses these parallels, which are smaller. Being smaller than the

equator, air is concentrated in a small volume. This makes the air to push out

with a lot of force which increases air pressure.

c. There is low pressure along 60

0

latitude despite the fact that it is 6660Km

form the equator and only 3330Km from the pole.

This is a temperate low pressure 60

0

North or South of the equator. This

develops a low pressure because the air that moves from the Polar Regions

due to rotation of the earth crosses a parallel which is longer. This makes air

to be spread far apart along 60

0

N or S of the equator as the air is spread

apart as a result of an increase in volume, the air pushes out with little force

hence low pressure even if it is closer to the polar region.

d. There is high pressure at the poles

The poles, 90

0

north or south of Africa have small space which makes air to be

squeezed thereby increasing pressure. Not only this, but also the factor of

temperature. The temperature is very low in these regions. This makes air to

contact and push out with a lot of force which increases pressure.

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Study the figure below which show the relationship between air pressure

and altitude (1995)

Height above

The seas level Barometric

Reading (mb)

(Km)

Explain the relationship shown above with reasons

As the altitude increases, pressure decreases. For example at sea level the

pressure is 760 millibars, at Y is 506 millibars which is at 2 Km, at $km the

pressure is 352millibars at 8 Km the pressure is 298 millibars. This shows that as

the altitude increases, pressure decreases. This is because at a low altitude the air

supports large columns of air which exerts a lot of force. As the altitude increases

the columns of air decreases. This makes air pressure to be reduced as less force

is exerted.

The figure below is a synoptic map of southern Africa. Use it to answer the questions

that follow (2002)

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Calculate the pressure gradient

980mb – 976 mb = 004

What instrument was used to arrive at the readings shown on the map

Barometer

On the map itself indicate the wind direction

Wind move from a high-pressure area to a low pressure. The arrow on the

map should come form outside which is a high pressure are to inside which is

a low pressure area ie

The figure below represents the earth. On the diagram itself: (1997)

a. Locate and name the main pressure belts (4)

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As shown above. The first thing should be to give degrees north or south of

the equator. Then the next should be to locate and name the doldrums, horse

latitudes, temperate latitudes and the polar latitudes.

b. Using arrows, locate and name the wind systems (4)

Winds which should be indicated are the-

a. Trade winds which blow the horse latitude towards the Doldrums

b. The westerlies which blow from horse latitudes towards the temperate low

pressure

c. The polar winds which blow the polar regions towards the temperate

- It should be known that the winds blow from high-pressure belts towards low-

pressure belts.

- It should also be known that under the Coriolis force, winds deflect to the right in

the northern hemisphere and to the left in the southern hemisphere.

- The winds are then known after the deflection. For example, south East polar,

north westerly, northeast polar, south westerly, north east trades and south east

trades.

Draw a stationary globe. On it insert and label any two of each of the

following in the southern hemisphere

a. Pressure belts

b. Prevailing winds (7 marks) (2007)

Requires the answers as the above question

Draw a labeled diagram to show the main parts of a mercury barometer (1989) (2004)

A mercury barometer is an instrument which is used for measuring atmospheric

pressure. It has the following important parts: calibrated glass tube, vacuum,

mercury, container that contains mercury and indicates of air pressure. The

diagram shows these parts.

Vacuum

Calibrated glass tube

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air pressure 76cm

Mercury container

remove

NOTE: When drawing neatness is required and the pointing and naming of the parts

should be accurate enough in order to get all marks. It should be known that, test

tubes, water should be far from this diagram.

Describe how the barometer you have drawn works

When the air pressure is high, a lot of force is exerted on the mercury in the

container. This makes the mercury in the container to go down and rise in the

glass tube whereby recording high pressure on the calibrated glass tube. When

the air pressure is low, little force is exerted on the mercury in the container. This

makes the mercury in the glass tube to go down and low air pressure is read off

on the calibrated glass tube.

What is lapse rate (19989)

This means the change of temperature, which decreases uniformly at the rate of

6.4

0

C per 1000m, with an increase in altitude

Study the table below and answer the questions that follow

Height in Meters

Pressure in Millibars

Temperature

5000

606

-9

3000

717

7

1500

842

16

Sea level

1012

25

Calculate

i. The pressure change from sea level to 5000 meters

Sea level = 1012

5000m = 606

Pressure change = 1012 – 606 millibars

= 406 millibars

ii. The temperature change from 5000meters to 3000 meters

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5000 meters= -9

0

C

3000 meters= 7

0

C

Temperature change = -9-7

= -16

0

C

What is the relationship between

a. Altitude and pressure (2 marks)

When altitude increases pressure decreases. For example, in the table at

sea level the pressure is 1012 and at 3000 meters the pressure is 717

millibars and at 5000 meters, the pressure is 606 millibars. This shows

that air increase in altitude makes pressure to decrease.

b. Pressure and temperature

When pressure decreases temperature also decreases. For example, at sea

level, according to the table, the pressure is 1012 millibars while temperature

is 25

0

C. At 5000 meters, pressure is 606 millibars and temperature is -9

0

C.

This clearly shows that when air pressure decreases, temperature also

decreases.

Give reasons for the above relationships (6 marks)

When altitude increases, pressure decreases because an increase in altitude makes

the column of air to be reduced. For example, at sea level the air pressure is high

because the place supports a large column of air. This in turn makes air push out

which a lot of force thereby increasing pressure. At the highest altitude such as a

mountain, there are few columns of air. This makes air to push up with little force

thereby lowering the pressure. Consequently, an increase in altitude lowers air

pressure.

When pressure decreases temperature also decreases. This occurs because when air

pressure decreases, the molecules does not push out with a lot of force and they are

apart. This makes friction between molecules to be reduced as they are far apart. This

in turn lowers the temperature as less heat is produced from the intermolecular

friction. Therefore, when pressure decreases temperature decreases.

Study the figure below that shows the main belts of the earth and answer the questions

that follow.

A B C F C B A

north south

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90

0

30

0

60

0

Name the latitudes at B,C and F

B= 60

0

temperature low pressure belt

C= 30

0

Horse latitude high pressure belt (sub-tropical)

F= 0

0

Doldrums low pressure belt or the equator

Explain why air pressure is high at C

This is because the air that comes from F as a result of temperature which is

higher, crosses parallel which are shorter in length. This makes the air to occupy

a small volume and push out with a lot of force. This in turn makes air pressure to

increase.

Explain why air pressure at F is always low

This is because along F, the temperature is always high, as the sun appears to be

shining direct. This heats up the air, which then expands and rises. This makes air

to occupy a large volume after rising and exert little force. This consequently

reduces pressure.

What causes low pressure at B despite the fact that it is closer to A than F

Air that escapes from A as a result of the rotation of the earth, obviously is thrown

to B. but at B the latitude is longer and the air occupies large space. This make

the pressure to be reduced because the air pushes out with little force, hence low

pressure even if it is closer to area A which is a high pressure region.

Study the map of Africa below and answer the questions that follow

Substitute with scanned

Trade winds

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Suggest the month of the year in North Africa in the diagram

June

What is the season in Malawi from the diagram it is cool dry season

It is cool dry season

What would be the direction of the ITCZ if the sun moved to the southern hemisphere

The ITCZ would move to the Southern Hemisphere too as a result of high

temperature. In addition, the development of low pressure following the apparent

movement of the sun.

Study the globe below which shows high pressure and low pressure belts and answer the

questions which follow (1983)

90

0

NP

90

0

SP

High pressure

Low pressure

Explain why there is a high pressure belt on the 30

0

latitudes where it is close to the

equator and a low pressure belt on the 60

0

latitudes close to the poles(8)

Check the above questions on air pressure for answers

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What is the significance of the movement of pressure belt on the globe in relation to the

season and winds (2002) (4)

The movement of pressure belt is because of the apparent movement of the sun.

This in turn brings a change in terms of pressure. A change in pressure

determines the type of season to be experienced and the movement of winds. For

example, when the sun appears to be in the northern hemisphere, a low pressure

is developed while southern hemisphere, a high pressure develops. Then wind

moves from the southern hemisphere, which is a high-pressure region to the

Northern hemisphere which is a low-pressure region. Such winds after crossing

the seas collects moisture and heavy rainfall occurs. Consequently, the southern

hemisphere where the wind comes experiences a different season as a result of the

shifting of the pressure belt.

Study the figure below which shows the modified pressure reading for southern Africa

(1993)

Draw lines joining places with the same atmospheric pressure

Look overleaf. The following are the important steps:

- Find the pressure gradient

- Establish where the high pressure is, that is, where the highest number is found, is

it at the center or outside

- Check the numbers before joining the places with the same pressure

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- The lines should cross each other but should just move very close

- Don’t jump any number

Key

H= high pressure

= wind direction

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What are these lines called

Isobars

What would be the force of wind when these lines are close to each other

It means there is a fast change of pressure from one area to another, and the

gradient is steep and the movement of wind is great or fast.

On the map itself insert H over an area of high pressure and point wind direction

On the map above, the arrow should come from inside. This is because the highest

number is at the center that is 1034 while the lowest is outside that is 1026. The

arrow should be pointing outside as wind moves from a high-pressure region to a

low-pressure area. Provide a key beside the map to show an area of high pressure

and wind direction

With the aid of a diagram describe how an aneroid Barometer works (8) (2002)

An aneroid barometer is an instrument which is used for measuring air pressure.

The instrument consists of the following important parts, Collapsible metal box

with very little air inside, a spring, a system of levers which includes the chain,

indicator or pointer and a graduated scale. The diagram below shows these parts

which make up an aneroid barometer.

Dial

Pinter chair

Air pressure

spring collapsible metal box

When the air pressure is high, air applies force on the collapsible metal box which

then goes inwards. This makes the spring to contract. When the spring contracts, it

pulls on a system of levers which in turn pulls a chain. The chain drives the pointer to

the right hand side indicating high pressure.

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When the atmospheric pressure is low, little force is applied on the collapsible metal

box. This makes the lid to go upwards, the spring to relax, making a system of levers

to drive the pointer to the left hand side indicating low pressure.

What two differences can be noticed between a mercury barometer and an aneroid

barometer?

a. A mercury barometer uses mercury in its operations while an aneroid uses the

collapsible metal box and a system of levers.

b. A mercury barometer, measurements are obtained in either centimeters or

millimeters and converted to millibars while as an aneroid, readings make be

obtained straight into millibars.

What two advantages can a mercury barometer have over an aneroid barometer

a. The mercury barometer is very accurate as compared to an aneroid barometer

b. A mercury screen while an aneroid cannot read well in a Stevenson screen

What two disadvantages can a mercury barometer have

a. It is very heavy and cumbersome, that is, it is difficult for it to be carried from

one point to another

b. A mercury barometer is not good for outdoor measurements

c. It only requires mercury for it to measure air pressure and no any other

liquid.

ATMOSPHERE ROTATION, REVOLUTION AND SEASONS

Define the following terms:

a. Aphelion: the point along the orbit when planets such as earth becomes farthest

from the sun

b. Perihelion: the point along the orbit when planets such as earth become closest to

the sun.

The circle below represents the earth with rays of light from the sun (1982)

replace

1 NP

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sun

rays

SP

1. For which date is the diagram correct

22

nd

December

2. Name the lines A,B,C and D,

A= Arctic Circle

B= equator

C= tropic of Capricorn

Circle of Illumination

3. On which two dates would the sun be directly overhead on line B

21

st

March and 23

rd

September

4. Referring to the numbers 1-4 in the figure above, give the number of a place, at

which:

a. The sun is below the horizon all day

b. Day light and darkness are both 12 hours long explain the alternation of day

and night (S)

Day and night are caused by the movement of the earth on its own axis once is 24

hours. This makes one part of the earth to face the sun and the other part to be away

from the sun. The part that faces the sun receives light and is termed as a day. The

other half which is away from the sun is in darkness and is termed as night. The

diagram below shows this alternation of day and night.

Direction of rotation

Sun’s rays

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When the earth rotates from west to east, the part that was in the darkness will face

the sun and will become day and that which was in the light will be away from light

and will be termed as night.

Describe the characteristics of the following types of seasons:

a. Summer

- Associated with high temperatures

- associated with heavy rainfall as a result of the development of low pressure that

make winds to converge in the area

- associated with longer dry hours and shorter night hours

b. Winter

- Associated with low temperatures, as the sun appears to be very far from the area.

This makes the rays to reach the earth in a slanting position, which reduces the

temperature.

- Long night hours and short day hours

- Very little rainfall

c. Autumn

- Characterized by decreasing temperature as the winter approaches

- Characterized by reducing rainfall

- Reducing day length and increasing night length, as the winter approaches

d. Spring

- Rising temperature as the summer approaches

- Some rainfall which increases when summer approaches

- Increasing day length and decreasing night length

Mention three seasons experiencing in Malawi and their months when such seasons are

experienced.

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a. Hot, Wet season which is experienced form November to April. This is so called

because during this time, the temperatures are high and there is rainfall. This

happens because the sun appears to be in the Southern hemisphere along the

tropic of Capricorn. Malawi lies in the Southern hemisphere.

b. Cool, Dry season which is experienced from May to July. During this time, the

temperatures are low, with dry conditions as the sun drifts to the northern

hemisphere. The drizzles experienced over Shire highlands are as a result of the

diverging South East trade winds, which then become the Chiperon winds.

c. Hot, dry season, experienced from August to October where temperatures start to

rise and dry conditions are experienced. There is no rainfall this time because the

low pressure is not fully developed.

Study the figure below which shows the position of the sun at different times of latitude

marked A, B, C and D for a town located at point X and answer the question that

follow: (1992)

X

Name the four seasons that will be experienced at X as the sun is overhead at points

A,B,C and D respectively

A= summer

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B= autumn

C= winter

D= spring

Give reasons for the characteristics of the above seasons

A= summer. As the place is in the northern hemisphere, at A is the tropic of Cancer.

This means, the sun will appear to be shining direct. Over A which will in turn bring

characteristics such as high temperature, heavy rainfall, longer day hours and

shorter night hours. This happens because the sun appears to be over the tropic of

Cancer 23

1

/2

0

N

B= Autumn: as the sun appears to come back from the northern hemisphere and

heading southern hemisphere, temperatures will start to decrease, rainfall starts to be

reduced, hours of daylight start to decrease while hours of night starts to increase.

This happens because winter season approaches.

C= winter: latitude along which C lies is the tropic of Capricorn. But place X is in

the northern hemisphere. The place X will experience winter season with very low

temperatures, little rainfall, long night hours and short day hours. These happen

because the sun appears to be far from X such that rays reach the place in a slanting

position.

D= Spring: which experiences an increase in the day hours and a decrease in the

night hours, an increase in temperature and an increase in the season is just about to

start as the sun returns to the tropic of Cancer 23

1

/2

0

North

Which areas would not experience the overhead sun (3)

These are the North Pole and the south pole because the sun appears to be very far

from such places

Study the figure below and answer the question that follows:

A

Page 69 of 159

B

5. State the seasons experienced at A

a. Hot, wet season

b. Cool Dry season

c. Hot dry season

6. State the four seasons experienced in B

a. Summer

b. Autumn

c. Spring

Explain why seasons experienced at A are somehow different from seasons experienced

in B

This is due to the differences in terms of latitudinal location. In A which can be

described as the tropics, temperature changes little such that what is described as

cold in the temperate, in the tropics it is cool. The amount of rainfall varies greatly in

the tropics than that in B which can be the temperate region these two factors

separates the two named regions in terms of climates.

Study the diagram below and answer the questions that follow:-

D NP

E

B

C

A SP

Name the lines marked A,B,E,D

A= the Antarctic Circle

B= the Equator

Page 70 of 159

E= the tropic of Cancer

D= Circle of illumination

When is the sun overhead line marked C

22

nd

December

When the sun is overhead line C, what season is in to the north of line E

It is winter season

When the sun is overhead line E, what season is it in Malawi

It is cool dry season

Study the figure below which is followed by the temperature data. Using these two,

answer the questions that follow (1992)

Page 71 of 159

Towns

Valencia

London

Berlin

Kiev

Orenburg

July max

15

0

C

16

0

C

19

0

C

20

0

C

22

0

C

January

max

7

0

C

4

0

C

-1

0

C

-6

0

C

-16

0

C

Describe the temperature changes between Valencia and Orenburg in Summer (2)

These towns are along 50

0

N. They experience summer in the month of July when the

sun appears to be overhead along the tropic of Cancer 23

1

/2

0

N. According to the

table, temperatures between Valencia and Orenburg increases as the distance

increases from the coast to inland. For example, Valencia has 15

0

C, while Orenburg

which is inland has a higher temperature of 22

0

C. This clearly shows, the increase in

temperature as the distance increases from the coast going inland.

Describe the temperature changes between the same stations in winter (2)

As the towns are in the Northern Hemisphere, January is the winter in the area.

According to the table, temperature decreases away from the coast, that is, as the

distance increases in land from the coast, temperature decreases. For example,

Valencia has 7

0

C, London, 4

0

C, Berlin -1

0

C, Kiev 16

0

C and Orenburg has the lowest

-16

0

C. This clearly shows that as the distance increases from the coast, temperature

decreases.

Give an account of why there are these changes in both summer and winter

In summer temperature increases as the distance increases from the coast. This is

because summers become hotter or inland, since the land absorb heat faster and

release it faster too. As the wind blow from the oceans to the land, it cools some of the

towns along the coast. Such winds do not usually reach inland hence higher

temperatures are inland.

In winter temperatures decrease with an increase in the distance from the coast. This

happens because in winter, the land loses heat faster. Since water absorbs heat slowly

in winter, water becomes warmer than the land. Warm air that blows towards the

land are responsible for the increase in temperature along the coast. Such warm air

does not reach towns which are far from the coast, hence lower temperatures

experienced in towns far from the coast.

In which direction does the earth move during revolution (2005)

It moves in an anticlockwise direction

Name the season that is experienced in south Africa at cape Town when the earth is

overhead at each of the following latitudes

a. Tropic of Cancer

Page 72 of 159

Winter season as South Africa lies in the southern hemisphere and the tropic of

cancer in the northern hemisphere. This makes South Africa to receive weak

slanting rays of the sun, hence winter season

b. Tropic of Capricorn

Summer season as the tropic of Capricorn is in the southern hemisphere and

South Africa also in the southern hemisphere. This makes the sun as if it shines

direct to South Africa, with high temperature and an increase I n the hours of day

light than hours of night.

c. Equator

Autumn as the sun is on its way to the tropic of cancer where winter will be

experienced in South Africa.

Define the term Solstice(2008)

This refers to the time when the sun appears to be stopping temporarily over the

tropics of cancer and the tropic of Capricorn in its apparent northward and

southward movement.

Identify the date when the summer solstice is experienced in the northern hemisphere

It is 21

st

June

With the aid of a well labeled diagram, show the position of the earth in relation to the

sun during the summer solstice in the Southern hemisphere and the major latitudes of

the earth (2008) (8)

Summer solstice in the southern hemisphere happens on 23

nd

December. During this

time the sun appears to be overhead along the tropic of Capricorn 23

1

/2

0

S. in other

words, the southern hemisphere tilts towards the sun where it experiences long hours

of day light and short hours of night, and an increase in temperature as the sun

appears to be shinning direct. The diagram below shows the position of the earth in

relation to the sun on 22

nd

December

Circle of illumination

23

1

/2

0

tropic of Cancer

Rays of the sun

0

Equator

23

1

/2

0

tropic of Capricorn

Page 73 of 159

5. Study the figure below which shows the position of the earth in relation to the

sun during 21

st

June.

a. On the same diagram provided below, insert

i. The suns’ rays showing where the noon day sun is overhead on 21

st

June (2)

ii. The line dividing the night from day and shade the area experiencing

night

Page 74 of 159

Compare the length of day at Philadelphia and Valdivia on 21

st

June (2)

Philadelphia will experience long hours of day light and short hours of night

while, as Valdivia will experience short hours of daylight and long hours of night.

Account for the difference (4)

Philadelphia will experience long hours of day light and short hours of night

because it is now summer in the area. As the place lies in the northern

hemisphere, it receives direct rays from the sun since the northern hemisphere has

tilted towards the sun, thereby receiving direct and more rays from the sun.

Valdivia, being in the southern hemisphere has tilted away from the sun. This

means Valdivia experiences winter with short hours of day light and long hours of

night. This happens because the place receives slanting and acute rays of the sun,

making it to appear as if it is far from the sun.

Page 75 of 159

Draw a diagram to illustrate the revolution of the earth around the sun by showing the

position of the earth at the two equinoxes and the two solstices. On your diagram insert

the following

i. The path or orbit

ii. An arrow showing the direction of the earth movement along the orbit

iii. An arrow to show the direction of the earth rotation at one position of the

earth

iv. The equator and the two tropics

v. The date at each position.

Revolution of the earth is the movement of the earth around the sun once in 365

1

/4

days or 366 days. The earth moves around the sun along its orbit. The earth moves in

an anticlockwise direction around the sun while rotating on its own axis from west to

east, once in 24 hours. The earth in its revolution appears on the equinoxes twice that

are on 21

st

March and 23

rd

September. It appears on the solstices twice, on 21

st

June

or 23

rd

June and 22

nd

December.

21

st

June is summer solstice in the Northern hemisphere and winter solstice in the

southern hemisphere. 22

nd

December is the summer solstice in southern hemisphere

and winter solstice in the northern hemisphere. The diagram below shows these:-

Direction of rotation from west to

east

Elliptical orbit

23

rd

March, autumn equinox

sun

21

st

June winter solstice

22

nd

Dec. summer

solstice

Direction of movement around the suns tropic of cancer

23

rd

Sept. spring equinox

Equator

Tropic of Capricorn

Page 76 of 159

The diagram above shows the revolution of the earth around the sun in the southern

hemisphere. If it were in the northern hemisphere 21

st

June would be summer, 23

rd

September would be autumn, 22

nd

December would be winter and 23

rd

March would

be spring with everything not changing.

6. Show how the earth revolution causes varying length of day and night at

different times of the year (7) (2001)

This question requires similar information and diagram as above only that an

emphasis should be on explaining that in summer days are longer and nights are

shorter and in winter nights are longer and days are shorter and explaining the

reason behind longer days and shorter nights or shorter days and longer nights.

Mention the latitude where the effect of earth revolution on the length of the day is not

experienced. Give a reason for your answer (3) 2000

It is the equator. This is because it cuts the earth into two equal halves in addition to

the fact that the area has the largest diameter. These facts result into fair distribution

of rays of the sun and therefore length of the day not experienced.

With the aid of diagrams, compare the variation in the length of the day at Aswan

23

1

/2

0

N and that of Windhoek 23

1

/2

0

S between 22

nd

December and 21

st

June (10) 2000

Aswan 23

1

/2

0

N is in North Africa and in the Northern hemisphere. Windhoek is in the

southern hemisphere. The two places have different length of day and night within a

year. On 22

nd

December, Windhoek experiences summer. It will have longer day

hours and shorter nights. This happens because the sun appears to be overhead along

the tropic of Capricorn 23

1

/2

0

S, where Windhoek is found. Thus direct rays will be

experienced at Windhoek with longer and warmer days, at the same time, on

December 22

nd

, Aswan experiences winter. Aswan will have longer nights hours and

short day hours which is in contrast to Windhoek. This happens because Aswan being

in the northern hemisphere appears to be very far from the sun. With this, it receives

weak slanting rays of the sun, hence winter.

On 21

st

June, Aswan enters summer with longer days and shorter nights as the sun

appear to be overhead along the tropic of Cancer 23

1

/2

0

N, where Aswan is found. At

the same time, Windhoek enters winter as it is in the southern hemisphere and

therefore far from the sun. The diagram below shows this:

Page 77 of 159

N 23

1

/2

0

N Aswan

0

Rays of sun

23

1

/2

0

S Windhoek

Position of the earth in relation to the sun on 22

nd

December. It should be noted that the rays

strike the earth at 23

1

/2

0

S. this makes Windhoek to experience summer and Aswan to

experience winter.

23

1

/2

0

N Aswan

Rays of the sun

0

23

1

/2

0

S Windhoek

This diagram above shows the position of the earth in relation to the sun on June 21

st

.

the rays of the sun strike direct at 23

1

/2

0

N. This makes Aswan to experience summer

with longer days and Windhoek to experience winter with shorter days.

Give a date when the two places (Windhoek and Aswan) above are likely to have no

variations in the length of the day

It is 23

rd

September or 23

rd

March as the sun appears to shine direct over the equator

What are seasons?

These are periods of the year which are characterized by special climatic conditions

such as dryness, wetness, hotness and coldness.

Mention two causes of seasons

i. The tilting of the earth to its axis at angle of 66

1

/2

0

ii. The revolution of the earth around the sun

How does each of these above contribute to the occurrence of seasons?

Page 78 of 159

i. The tilting of the earth’s axis at an angle of 66

1

/2

0

. The earth’s axis doesn’t

stick straight up from the orbital plane. It tilts about 23

1

/2

0

from the straight

up position and 66

1

/2

0

from the orbital plane. this tilt and the earth’s motion

around the sun causes the change of seasons. This causes seasons in that part

of the earth tilts towards the sun and the other part away from the sun. for

example, on 21

st

June, the northern hemisphere tilts towards the sun and

experiences summer with longer days and warmer conditions, while the

southern hemisphere tilts away from the sun and experiences winter with short

days and colder conditions. From 22

nd

December to 21

st

march, the northern

hemisphere is tilted away from the sun and experiences winter. Within the

same period, the southern hemisphere experiences summer as it is tilted

towards the sun.

NOTE: when the question requires an illustration, draw that of the revolution

of the earth around the sun, with dates and seasons.

ii. The revolution of the earth or apparent movement of the sun is the other

cause. In a year, the sun appears to be moving between the tropic of Cancer

23

1

/2

0

N, the equator 0

0

and the Tropic of Capricorn 23

1

/2

0

S. This in turn

brings the unequal distribution of light and temperature which brings about

different seasons. The sun appears to be overhead along the tropic of Cancer

23

1

/2

0

N. thus the northern hemisphere has summer solstice on this day while

the southern hemisphere has its shortest day and longest night- winter

solstice. The sun then appears to be overhead at the tropic of Capricorn in the

southern hemisphere. Thus, the southern hemisphere experiences summer and

northern hemisphere winter. The diagram below shows the apparent

movement of the sun.

21

st

June 21

st

June

23

1

/2

0

N tropic of Cancer

0

23

rd

Sept 23

rd

Mar equator

The apparent movement of the sun

23

1

/2

0

S

December tropic of Capricorn

The sun appears to be overhead on the equator on 21

st

March and 23

rd

September of each

year. The length of the days and the nights are equal. These two days (21

st

march and 23

rd

September) are called equinoxes.

Apart from seasons, give two other results of the revolution of the earth around the sun

and its inclination of its axis.

Page 79 of 159

i. changes in the midday sun’s altitude at different times of the year

i. Varying lengths of day and night at different times of the year.

Apart from days and nights, give other three things that would happen should the

earth stop rotating on its own axis

i. There would be no difference of 1 hour between two meridians which are 15

0

apart

ii. There would be no deflection of winds and ocean currents as the coriolis force

would not exist

iii. There would be no daily rising and falling of the tides.

LATITUDES, LONGITUDES, GREAT CIRCLES AND CIRCULATION OF TIME

Define the following terms:-

i. Longitudes

These are angular distances measured in degree east or west of the prime

meridian (0

0

)

ii. Latitudes

These are angular distances of a place on the earth’s surface north or south of

the equator measured in degrees from the center of the earth.

Give three characteristics of latitudes

i. They are always parallel to each other, that is why they are also called

“parallels”

ii. They run from east to west intersecting longitudes at right angles

iii. They decrease in length as they approach the polar regions

iv. They appear to be small circles except the equator which is great circle.

Give three examples of latitudes

i. The tropic of Cancer (23

1

/2

0

N)

ii. The tropic of Capricorn (23

1

/2

0

S)

iii. The Arctic Circle (66

1

/2

0

N)

iv. The Antarctic circle (66

1

/2

0

s)

A cyclist is at a certain town 32

0

south of the equator. How far is it from the equator?

Since 1

0

= 111Km

Therefore 32

0

= 32

0

x 111 Km

1

0

= (32 x 111) Km

= 3552 Km

Page 80 of 159

NOTE: when calculating the distance using latitude from the equator, it is important to

remember the following:

There are 180

0

North or South of the Equator and the surface distance between the

South Pole and the North Pole is 20,000Km.

Therefore to find the length of a latitude

(20,000 x 1

0

)

180

0

= 111Km or 112Km

Therefore, there are 111Km or 112Km between any two degrees of latitude.

At equator 0

0

the distance is 110 Km, at 45

0

is 111Km and at the poles is 111.7 Km

and the average is taken as 111Km

A tourist visits a game reserve at latitude 54 degrees 30 seconds. How far is it from the

equator?

1

0

= 60 seconds or 1

0

= 60’

1

0

= 111 Km

54

1

/2

0

= 111 x 54

1

/2

= 6049.5Km

= 6050 Km

It is = 6050 Km from the equator

Find the local time of a place 60

0

W if the time at Greenwich (0

0

) is 6:00 p.m

Time at Greenwich (0

0

) = 6:00 pm

Longitude of a place = 60

0

W

Time difference = 60

0

/15

0

= 4hrs

Time at 60

0

W = 6:00 – 4 hrs

= 2:00 pm

What would be the time at town B which is 30

0

E of town A. when time at town A is 3Pm

Time at A = 3pm

Longitude of town B = 30

0

E

Time difference = 30

0

/15

0

= 2hrs

Time at town B 30

0

E = 3:00 + 2

= 5:00pm

Page 81 of 159

Or = 17:00 hrs

What will be the time at 30

0

E if the time is 12:00 noon at 0

0

longitude

0

15

0

E 30

0

E 45

0

E

12:00 noon

Longitude of a place = 30

0

E

Time at Greenwich = 12 noon

Time difference in hours = 30/15

= 2hrs

Longitude of a place = 30

0

E

= 12:00 + 2hrs

= 14:00

0

15

0

E 30

0

E 45

0

E

12:00 noon 14:00

Calculate the time at 30

0

E if the time is 4:00 pm at 45

0

E

0

15

0

E 30

0

E 45

0

E

? 4:00 pm

Longitude of a place = 30

0

e

Time at 45

0

E = 4:00pm

Difference in longitude = 45

0

- 30

0

= 15

0

Time difference = 15

0

/15

0

= 1hr

Page 82 of 159

Time at 30

0

E = 4:00 pm – 1 hr

= 3:00 pm

Diagrammatically

0

15

0

E 30

0

E 45

0

E

3:00 pm 4:00 pm

Calculate the time at X whose longitude is 45

0

W when the time at Q 73

0

E is 14 hrs or

2:00 pm

Longitude of a place = 45

0

W

Time at longitude q 73

0

E = 14 hrs

Difference in longitude = 45

0

E – 0

0

+ 73

0

W

(Since one place is to east and another to the west)

= 45

0

E – 0

0

+ 73

0

W

= 118

0

Time difference = 118

0

/15

0

= 7hrs 13

0

= 13/15 x 60 (to find minutes 1

0

= 60’)

Therefore time = 52 minutes

Time at 45

0

W = 14:00 – 7:52

= 6.08

Time at 45

0

W = 6.08

(note 52 minutes are subtracted from 60 minutes that make 1

0

)

What is the time at 15

0

W when the time at 105

0

W is 16:00 hrs

Longitude of a place = 15

0

W

Time at 105

0

W = 16:00

Difference in longitude = 105

0

– 15

0

W

= 90

0

Time difference = 90

0

/15

0

= 6hrs

Time at 15

0

W = 6:00 + 6hrs

= 12:00 noon

Page 83 of 159

NOTE: time is added because it is from a higher degree to a lower degree even if it is in the

west.

105

0

W 30

0

W 15

0

W 0

0

15

0

E

16:00 ?

Therefore, time at 15

0

W = 12:00 noon

Calculate the time in New York 75

0

W when it is 18 hrs in Sydney, Australia 150

0

E

Difference between longitudes between two places = 75

0

– 0

0

+ 150

0

(since one place is to the east and the other to the west, the Greenwich (0

0

) must be

reached first)

= 225

0

Difference in time = 225

0

/15

0

= 15hrs

Time in New York = 18:00 – 15 hrs

= 3:00 am

Subtraction is done due to the movement from a higher to lower degree

Suppose a Malawian football team is playing Ghana in Accra (0

0

) and the game is

scheduled for 3:00 Pm Ghanaian time. What time will be in Malawi (35

0

E) at the kick

off?

Time at Ghana (0

0

) = 3:00pm

Longitude of Malawi = 35

0

E

Time difference =35

0

/15

0

= 2hrs 33 minutes

Malawi 35

0

E = 3:00 + 2:33 hrs

= 5:33 pm

A football match between Malawi and Ghana kicks off in Accra, Ghana (0

0

) at 5:00 pm

local time. What will it be in Malawi, 30

0

E? show your working (1992)

Time in Ghana (0

0

) = 5:00 pm

Longitude of Malawi = 30

0

E

Time difference = 30

0

/15

0

= 2hrs

Since Malawi is to the east = 5:00pm + 2 hrs

= 19:00

Page 84 of 159

0

15

0

E 30

0

E 45

0

E

5:00 pm 7:00 pm

1. A football match will be played in town N which is along the Prime meridian

(0

0

). It will start at 10pm. Calculate the time at which people in Town P 50

0

W

and town Q 20

0

E should switch on their televisions to watch this football match

(6 marks) 2008

Since town N is along the prime meridian it is (0

0

)

Time at town N (0

0

) = 10 pm

Longitude of town P = 50

0

W

Time difference = 50

0

/15

0

= 3:33hrs

Since P is to the west of N = 10:00 pm – 3:33hrs

= 6.27 pm

Longitude of town Q = 20

0

E

= 20

0

/15

0

= 1:33 hrs

Since the town is to the east = 10: pm + 1:33 pm

= 11:33 pm

Therefore town P must switch the television at 6:27 pm while town Q at 11:33 pm

60

0

50

0

45

0

W 30

0

W 15

0

W 0

0

15

0

E 20

0

30

0

E 45

0

E 60

0

E

P N Q

6:27 pm 10:00 pm 11:33pm

2. Suppose an international football match is to be held in Accra, Ghana (0

0

) and is

scheduled to start at 2: pm on Sunday, 28

th

January 2001. Imagine that contester

will come from country A (165

0

W) and country B (180

0

E). Calculate the time

date and day when the listeners in each of the two countries can tune in their

radios for the start of the match (10).

Using the diagram to solve the problem

165

0

W 30

0

W 15

0

W 0

0

15

0

E 30

0

E 45

0

E 60

0

E

Page 85 of 159

2:00 pm ??

Sunday

Time at Accra, Ghana = 14:00

Longitude of place A = 165

0

W

Time difference in hours = 165

0

/15

0

= 11 hrs

Place A is to the west = 14:00 – 11:00

= 3:00 am

Country A should switch on their radios on 29

th

January, Monday 3:00 am

Longitude of country B = 180

0

E

Time difference in hours = 180

0

/15

0

= 12hrs

Since the country is to the east = 14:00 + 12 hrs

= 26:00

= 26:00 – 0:00 as it passes midnight

= 02:00 hrs

Country B would listen to the match on 29

th

January, Saturday 02:00 am 2001

165

0

W 0

0

180

0

E

3:00 am (Monday) 14:00 (Sunday) 02:00 am (Saturday)

Given that at 18

0

W time is 12 noon, what is the time at 10

0

W and 26

0

W?

26

0

W 18

0

W 10

0

W

12 noon

i. Time at 10

0

W

Page 86 of 159

Difference in location = 18

0

- 10

0

= 8

0

Time difference = 4x8

0

= 32 minutes

Add 32 minutes to the time at 18

0

W to find time at 10

0

W because 10

0

W lies to the

east of 18

0

W. This shows that time at 10

0

W is 32 minutes afternoon that is 12:32

pm

ii. Time at 26

0

W

Difference in location = 26

0

- 18

0

= 8

0

= 32 minutes

Subtract 32 minutes from the time at 18

0

W to find time at 26

0

W because 26

0

lies to

the west of 18

0

W. this shows that time at 26

0

is before noon, that is 11:28 am.

NOTE THE FOLLOWING WHEN CALCULATING LOCAL TIME FROM

THE GREENWICH MEAN TIME (GMT)

- Different place located on different longitudes or meridians have different

local times at any given time.

- Two places located on two longitudes 15

0

apart have time difference of one

hour

25

0

E 40

0

E

8:00 am 9:00 am

- The earth completes its rotation in 24 hours therefore in 1 hour the earth turns

360/24 = 15

0

- Longitudes are therefore located 15

0

apart

- Going towards the east time is added while towards the west in subtracted.

This is because the earth rotates from west to east. This means that the east

sees the sun first and w3est later. Therefore time should be calculated from the

Greenwich Meridian or prime Meridian (0

0

) either going eastwards or

westwards. Time is ahead of the Green witch meridian when going eastwards

and behind the Greenwich meridian going westwards.

0

Page 87 of 159

West East

Subtract add

- When it is 2 pm along longitude 0

0

, to the east it is after this time but to the

west it is before this time. To find time at a place to the East of longitude 0

0

,

time difference should be worked out first between that place and longitude 0

0

.

To the west time is subtract from the time along longitude 0

0

. For example

60

0

W 30

0

W 15

0

W 0

0

15

0

E

3pm

It is 3pm along 15

0

W. What are the times for other longitudes? The longitudes

are spaced 15

0

a part or 1 hour apart.

i. To find time for longitude 0

0

add 1 hour to the time for longitude 15

0

W

because 0

0

lies to the east of 15

0

W. The time along 0

0

longitude is (3+1) pm or

4Pm.

ii. To find time for longitude 30

0

W subtract 1 hour from the time for longitude

15

0

W because going westwards time is subtracted so the time at 30

0

W is (3-1)

pm or 2 pm.

iii. What is the time at longitude 60

0

W when time at 15

0

W is 3 pm.

Difference in location = 60

0

- 15

0

= 45

0

Time difference = 45/15

= 3 hrs

Time at 60

0

W = (3-3) pm

= 0

= 12 noon

- In 1 hour the earth turns 15

0

of longitude. This means that every 4 minutes the

earth turns 1

0

of longitude (1 hr = 60 minutes)

= 60/15

= 4 minutes

Journalist leaves a village at longitude 105

0

west at 10:00 am arrives at a certain island

at 2:00 hrs. At which longitude is he at this time.

Working:

Page 88 of 159

The longitude is ahead of the prime meridian, therefore time will be added

Time difference =0

0

- 105

0

= 105

0

Time difference = 105

0

/15

0

= 7 hrs

Time at 105

0

= 10:00 am

The time is ahead of GMT

= 7 hrs + 10:00 am

= 17:00 hrs

Difference in time with that of an island

20: - 17 hrs

= 3hrs

If 1 hr = 15

0

3hrs = 3 x 15

0

= 45

0

The journalist will be at longitude 45

0

east

A tourist leaves a historical site at 5:00 pm at a longitude 45

0

E of the Greenwich

meridian. At what time does he arrives at longitude 150

0

W of prime meridian?

Difference in longitude = 45

0

– 0

0

+ 150

0

W

One place is to the east and the other to the west

= 195

0

Time difference = 195

0

/15

0

= 13 hrs

Longitude required to find time = 150

0

W

Since the place is to the west, time must be subtracted

17:00 – 13:00 hrs

= 4:00

Therefore, the tourist arrives at longitude 150

0

W of the Prime meridian at 4:00 am

Calculate the longitude of a place whose time is 24hrs when the time at6 30

0

E is 15 hrs

Time difference between the two places = 24:00 – 15:00 hrs

= 9hrs

If 1 hr = 15

0

9 hrs = 15x9

= 135

0

30

0

E = 135

0

+ 30

0

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=165

0

E

Longitude of a place is 165

0

E

What is the longitude of a place G whose time is 2:00 am Sunday when the time at 30

0

W

is 22:00 hrs (10pm) on Saturday

Time at longitude G = 2:00 am

Time at 30

0

W = 22:00 hrs

Difference in time = 24:00 – 22:00 + 2hrs

The time has past midnight

= 2hrs + 2hrs

= 4hrs

If 1 hr = 15

0

4 hrs = 15x4

= 60

0

Since the time shows two days involved and the degrees show that both the west and the east

of the prime meridian are involved, a different approach is used

60

0

+ 0

0

– 30

0

(these are 30

0

W)

= 30

0

E

Calculate the longitude of a place whose time is 8: 00 am. The time of another place

found at longitude 120

0

W is 4 am.

Difference in times given = 8-4

= 4 hrs

If 1 hr = 15

0

4hrs = 15x4

= 60

0

Longitude of a place = 120

0

– 60

0

(Because it is from a higher longitude4 to a lower longitude towards the prime

meridian)

WEATHER INSTRUMENTS

Clearly state what do you understand by the following terms:

i. Humidity

This is the amount of water vapor in the air

ii. Precipitation

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This is the falling of all frozen and liquid forms of water from the

atmosphere to the earth’s surface. It involves rain, fog, snow, hail, drizzle

and sleet.

iii. Atmospheric pressure

This is the force exerted by air on to the earth’s surface

All weather stations have a Stevenson screen:

i. Describe its structure

It is a box found in all weather stations. It is put 121cm above the ground,

painted white in order to reflect light, made up of louvers on all sides in

order to allow air to circulate. The roof is made up of double boarding to

prevent the sun’s heat from reaching the inside of the screen.

ii. Name the instruments it contains

a. Wet bulb thermometer

b. Dry bulb thermometer

c. Minimum thermometer

d. Maximum thermometer

e. Mercury barometer

iii. Briefly describe the nature of its location

It has to be located in an open place where the air is free to circulate. It

should be away from trees and buildings as these would block the elements

of weather to be measured. It should be put at a height of 121 cm or 1.2 m

from the ground. This is done in order to protect it from being knocked

down by cars in addition to allowing free circulation of air below.

Carefully, explain the meanings of the following terms

i. Mean daily temperature

This is the average of maximum and minimum temperatures recorded in a

day or 24 hours. It is found by adding the minimum and maximum

temperature of the day and then halved. For example,

Maximum 31

0

C

Minimum 29

0

C

Mean daily (diurnal) temperature = 31 + 29

0

c

2

= 30

0

C

ii. Diurnal temperature range

This is the difference between maximum and minimum temperature

recorded in a day or in 24 hours. It is also called the daily temperature

range, calculated by subtracting the minimum temperature for a day from

the maximum temperature for a day. For example

Maximum 31

0

C

Hygrometer

Six’s thermometer

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Minimum 29

0

C

Daily temperature range = 31 – 29

0

C

= 2

0

C

iii. Mean monthly temperature

This is the sum of mean daily temperatures for one month divided by the

number of days in that month

= sum of daily temperature for 1 month

Number of days in a month

iv. Mean annual temperature

This is the sum of mean monthly temperatures for one year divided by the

total number of months in a year

= sum of mean monthly temperatures for 1 year

12

v. Mean annual range of temperature

This is the difference between the highest mean monthly temperature and

the lowest mean monthly temperatures in a year.

= highest mean monthly temp – lowest mean monthly temp.

vi. Relative humidity

This is the ratio or relationship between the actual amount of water vapor

in a given volume of air and the amount which it can hold at a given

temperature

vii. Absolute humidity

This is the actual amount of water vapor in the air at a particular time

A weather station contains the following instruments: wind vane, six’s thermometer and

a hygrometer:

Draw diagrams, label the instruments and explain how they are used to weather

records.

i. A wind vane

A wind vane is an instrument, which is used for indicating the direction of wind. It

consists of a horizontal rotating arm pivoted on a vertical shaft. The rotating arm

has a tail at one end and a pointer at the other. Below the rotating arm there is a

fixed framework indicating the cardinal points of a compass. The important

cardinal points are North (N), South (S), West (W) and East (E). although not

shown in the wind vane, there are other important directions between the cardinal

points such as North East (NE), North West (NW), South East (SE) and South

West (SW). The diagram below shows a wind vane

Page 92 of 159

Freely moving arrow

Tail pointer

Vertical shaft

When the wind blows, the arm swings until the pointer faces the wind. When the

wind blows from the north, the pointer points to the north. When the wind blows

from the east the pointer points east. In whatever direction the wind blows from,

the pointer points there. In the diagram above, the wind is blowing from

Northeast. Such wind can be called the North Easterly wind.

ii. The Six’s thermometer

This is a combination of maximum and minimum thermometer. It is used for

measuring the temperature of the day in degrees Celsius. It consists of the two

limbs, the left hand limb that records the minimum temperature and the right hand

limb, which records the maximum temperature of the day. Both limbs contain

alcohol, mercury and a metal index. At the top of the right hand limb there is an

empty space called a Vacuum. The diagram below shows a six’s thermometer.

Maximum minimum

Vacuum

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Conical bulb

Alcohol

Metal index

Mercury

When the temperature rises, the alcohol in the left-hand limb expands and pushes

the mercury down the left-hand limb and up the right hand limb. The alcohol in

this limb also heats up and part of it is vaporized and occupies the space in the

bulb called vacuum. The maximum temperature is read from the scale on the right

hand limb but at the bottom of the metal index. In the diagram above, the

maximum temperature is 20

0

C.

When the temperature falls, the alcohol in the left- hand limb contracts and some

of the alcohol vapor in the conical bulb liquefies. This causes the mercury to flow

from the right-hand limb to the left. Read from the scale on the left hand limb but

at the top of the metal index. In the diagram above, the minimum temperature is

10

0

C.

To reset the thermometer, a magnet is used to pull the metal indices to mercury

level. The movement of the alcohol does not make the metal indices to move. The

mercury moves these.

iii. The Hygrometer

This is an instrument, which is used for measuring the amount of water vapor in

the air. It consists of two thermometers, the wet bulb and dry bulb thermometer.

The wet bulb thermometer’s base is wrapped in thin muslin, which dips into a

small container of water. The dry bulb thermometer has no muslin. Both

thermometers contain mercury. The diagram below shows the hygrometer.

Page 94 of 159

Muslins

Container

Water

The hygrometer measures humidity through the use of wet and dry bulb thermometer

and the special tables prepared. When temperature rises, that is, when air is not

saturated, moisture evaporates from the muslin or cloth, which in turn cools the wet

bulb. Mercury in the wet bulb contracts when evaporation is taking place.

Temperature is therefore lowered in the wet bulb by this evaporation. But the dry bulb

is not affected in any way by the evaporating water.

When the air saturated, that is, full of moisture, no evaporation takes place from the

muslin. The two thermometers then show the same reading as the dry bulb cannot

also rise. The differences in temperature readings of the two thermometers are used to

determine relative humidity using special tables. Generally when the two

thermometers read the same, the air is saturated, when the difference in the readings

of the two thermometers is small, it means that relative humidity is high and when the

difference in the reading from the two thermometers is large, it means that relative

humidity is low.

Briefly explain the meaning of each of the following statements:

a) A Stevenson screen should be at least 1.2 meters above the surface,

its sides should be louvered and it should be painted white

A Stevenson screen, a weather instrument box has to be placed at 1.2 meters in order

to allow free circulation of air and to make it visible enough so that a car should not

knock it down. Its sides should be louvered in order to allow air to flow in and out

easily in addition to preventing direct sunlight into the screen. It should be painted

Page 95 of 159

white in order to reflect sunlight which would destroy the instruments inside should it

be allowed.

b) A six’s thermometer is a combination of maximum and minimum

thermometers

This is a combination of maximum and minimum thermometer. These are joined

together in a u- shaped tube. The maximum measures the highest temperature of the

day and the minimum measures the lowest temperature of the day.

c) When the air is saturated wet and dry bulb thermometer should

read the same

When the air is saturated, it means there is a lot of water vapor in the atmosphere.

This makes water not to evaporate from the muslin or cloth in order to cool tha wet

bulb. The dry bulb also does not rise, as the mercury is not heated up for it to rise.

The result is that the two thermometers read the same or there is no difference. This is

interpreted as 100% and air is saturated.

1. Describe and name the instrument that is used for measuring rainfall

Rainfall is measured by using an instrument called a Rain gauge. A Rain gauge

consists of a rainwater-collecting jar, metal container, a funnel and a separate

measuring cylinder. The collecting jar is below the ground level in order to

prevent evaporation of water after being collected. The diagram below shows a

rain gauge.

Diagram.

13cm Funnel

Page 96 of 159

Copper cylinder

30Cm

Metal container

Ground

Collecting jar (bottle

Measuring cylinder

When rainfalls, the funnel collects the rainwater drops and directs them into the

jar. The water in the jar is then carefully poured into the measuring cylinder, and

the amount is read off on the side of the measuring cylinder at an eye level.

Rainfall is measured in millimeters (mm) the rain gauge should at least be 30Cm

above the ground in order to avoid splashing. The instruments should be sited

well away from tall buildings, high trees and other objects, which would shelter it.

This can help avoid wrong readings due to in splashing of raindrops form tree

leaves or roofs of buildings

Page 97 of 159

Define the following terms:

i. Isotherms: these are line on a map joining all places of equal temperature

readings

ii. Isohyets: lines drawn joining places of equal rainfall amounts on the

paper

iii. Isohels: a line drawn through places with same duration of sunlight

iv. Isoneph: a line drawn on a map joining places having equal cloudiness

over a certain period of time

v. Isobar: a line joining places of the same air pressure on the paper

vi. Anemograph: this is a self recording anemometer, recording the speed of

wind in Km/hr

vii. Psychrometer: this is a more accurate instrument for measuring humidity

apart from hygrometer.

What instrument would you use to measure each of the following:

i. Wind velocity = cup anemometer

ii. Relative humidity= hygrometer

iii. Atmospheric pressure= Barometer

iv. Sunshine= Campbell sunshine recorder

v. Wind direction= wind vane

Explain two reasons why weather stations are important (1993)

Weather stations give weather reports, which are important in the following

areas:

- The direction of wind tend to control the pattern of trade routes especially in

shipping

- Help farmers to prepare for their seasons in the cultivation of crops

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- Temperature, humidity and rainfall may either promote or discourage certain

pests and diseases which may destroy crops and animals.

- The safety of modern air travel is tied to accurate weather conditions and

records from ground stations.

At a weather station in Malawi in a certain month, there were 7 days of

mwera, 10 days of Southeast winds, 3 days of East winds, 5 days of North eat

winds and 4 days of north west winds. 4 days were calm.

draw a wind rose recording the wind frequency and explain how it is done (6) (1995)

a wind rose is an instrument used for recording the direction of prevailing winds of a

place, over a period of one month. It consists of eight compass directions

When the wind direction has been obtained, a line is drawn on the cardinal point from which

the wind blew. The cardinal point with the largest number of lines represents the direction of

the prevailing wind for that month. For example in the wind rose drawn, most of the wind

came from southeast as it has the highest frequency. The place had the south easterly

prevailing winds. The number of calm days when the wind did not blow is indicated at the

center. In the diagram above, 4 days were calm days. Sometimes instead of indicating lines

dates are recorded when the wind blew.

The following wind directions were recorded at a weather station for the month of

September. Use the information to draw a wind rose.

Page 99 of 159

DATE

DIRECTION

DATE

DIRECTION

DATE

DIRECTION

1

NE

11

NW

21

-

2

S

12

NW

22

S

3

-

13

NW

23

S

4

S

14

S

24

E

5

N

15

-

25

W

6

W

16

-

26

NW

7

E

17

S

27

E

8

SW

18

-

28

NW

9

-

19

E

29

SW

10

S

20

N

30

-

A wind rose is an instrument which is used for recording the direction of wind. It has eight

main cardinal points. The date is recorded on the rectangle representing the cardinal point

from which the wind blew. The number of days when the wind did not blow are written on

the center. The diagram below represents the wind rose for the month of September.

Page 100 of 159

In this wind rose, south had the largest number of frequencies. In the month of September, the

southerly wind blew most. There were seven days when the wind did not blow strongly so as

to be noticed. The days are on 3

rd

, 9

th

, 15

th

, 16

th

, 18

th

, 19

th

, and 30

th

, of September. The days

are counted and recorded on the center. 7 which is at the center represents these seven calm

days.

The table below shows wind direction frequencies for Zungu town (2007)

Compass

direction

N

S

E

W

NE

NW

SE

SW

CALM

frequency

5

3

4

3

7

2

1

3

2. State any two instruments which are to collect the data in the table (2) (2007)

- Wind vane

- Wind sock

- Weather cock

3. Prepare a wind rose for the data

A wind rose is an instrument used for recording the direction of wind. It consists of

eight rectangular shaped polygons. Each represents one cardinal point. The side

Page 101 of 159

which the highest frequency represents the direction of the prevailing wind for that

month below is a diagram of a wind rose for Zungu town.

According to the figure above, the wind blew most from North east and it is called the

north easterly wind. This is because Northeast has the highest frequency. The number

inscribed in the center, 3, represents the number of calm days when the wind did not

blow with, a lot of force to determine its direction.

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PREVAILING WINDS

Give three characteristics of the trade winds

- Trade winds tread or follow a regular pattern. This is because the word

“trade” comes form Saxon word “tredan” which means tread or follow a

regular path.

- They blow from the Horse latitudes high-pressure belts towards the Doldrums

low-pressure belt from both north and south.

- They are deflected to the right to become the north east trade winds in the

northern hemisphere and to the left to become the South east trade winds in

the southern hemisphere

- They sometimes contain depressions or cyclones.

What is the importance of westerly winds give two reasons.

- Good belts for long distance flying trans- oceanic and transcontinental

aeroplanes use the belts. The vessels and aeroplanes move fast in the direction

of the westerlies, saving time and fuel.

- In the Mediterranean climate, the westerlies help to bring rainfall in winter.

Page 103 of 159

What are the two problems brought by the westerly winds

- Once in a while, the area is plagued by tropical storms called hurricane or

typhoons. These cause a lot of destruction to buildings and often kill people.

- When ships sail against them, the journeys become slow and a lot of fuel is

used. There is also a danger of ships capsizing especially true in the southern

hemisphere and regularity throughout the year over roaring forties or furious

fifties or screaming sixties. The speed of aeroplanes is also reduced while fuel

is increased due to strong head winds.

Study the figure below and answer the questions that follow

Arrows showing wind circulation

C B A B C

X 90

0

60

0

30

0

30

0

60

0

90

0

X

Complete the diagram to show wind circulation in the world.

Indicate by arrows. It should be known that wind moves from a high

pressure are to a low-pressure area. First, take note of the pressure belts,

and then using arrows show the direction as above.

Why does wind blow from B to A on the surface of the earth

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This is because B is a high-pressure belt and A is a low pressure belt. This

makes wind to blow form B, a high pressure belt to A, a low pressure

region on the surface of the earth

Explain why wind blows from A to B on the upper atmosphere

After rising on A, the wind meets colder atmospheric layers of the earth

since temperature decreases with increase in altitude in the troposphere.

This makes the rising air to be cooled, becoming more dense. As it is

heavier in the upper atmosphere, it then sinks back to B, hence wind

moving from A to B in the upper atmosphere.

Explain general characteristics of the prevailing winds.

- Move from high-pressure belts to low pressure belts. For example, the trade

winds move from high-pressure belts of horse latitudes and blow to the

Doldrums low-pressure belt.

- They deflect to the right hand side in the northern hemisphere and to the left in

the southern hemisphere.

What are the characteristics of westerly winds. Mention any three (6) (1997)

- They blow from the horse latitude high-pressure belt to temperate low-

pressure belt.

- They are deflected to the right to become the south westerly in the northern

hemisphere and to the left to become the north westerlies in the southern

hemisphere

- They are both variable in both direction and strength

- They contain depressions or cyclones.

Of what importance are trade winds, mention any two (4)

- As they move from the horse latitude towards the doldrums low pressure belt,

they bring heavy convectional rainfall. This makes areas along the equator to

experience a lot of rainfall.

- Good for sailing vessels and aero planes which follow the direction of the

trade winds. This saves time and fuel.

Page 105 of 159

What names are given to the following prevailing winds after deflecting in the southern

hemisphere

- Trade winds = South East trade winds

- Westerlies= north westerly winds

- Polar winds= south east polar winds

What do you understand by the term prevailing winds

These are winds that blow more often than any other type of wind on the

globe.

Illustrate the global pattern of the following with a diagram

a. Prevailing winds (6)

b. Pressure belts (8)

Prevailing winds are those that blow more often than any other type on the

globe. The most important prevailing winds are the polar, trades and

westerly. On the globe, prevailing wind blow from high pressure belts such

as the horse latitudes, the polar high pressure, towards the low-pressure

belts such as the temperate low pressure and the Doldrums low-pressure

belt. The globe below illustrates the prevailing winds with Coriolis force

into effect.

Polar high-pressure belt

Temperate latitude high pressure belt

horse lat. High pres. belt

Doldrums low pres.

Horse lati. Low pressure .

Page 106 of 159

Temperate low pressure belt

Polar high pressure belt

After deflection, the winds acquire new names such as northeast polar,

southeast trade winds, north westerlies.

Explain why:-

1. Winds do not blow directly towards the poles or the equator (1987)

This is due to rotation of the earth, which makes Coriolis force to be in effect. This

force makes winds to deflect to the right in the northern hemisphere and to the left in

the southern hemisphere. This makes winds not to blow direct towards either the

poles or the equator.

2. Wind belts shift that position latitudinaly

Wind belts are because of pressure belts which in turn occur because of the position

of the sun. When the sun appears to move whether to the northern hemisphere or to

the southern hemisphere, it brings about differences in terms of pressure. This

difference creates pressure belts. For instance, when the sun appears to be in the

northern hemisphere, there is high temperature. This creates a low pressure. Wind

then moves from the high-pressure belts in the southern hemisphere to the northern

hemisphere. This brings about changes in wind belts because when the sun will

appear to be in the southern hemisphere, a low pressure will be created while the

northern hemisphere will have a high pressure. This makes wind to move from the

northern hemisphere to the southern hemisphere.

Page 107 of 159

LOCAL WINDS

mention two general characteristics of local winds

- They affect only limited areas and blow for short periods of time.

- They are named after the local names in areas where they exist

- They are caused by the immediate influences of the surrounding topography

or relief

- They moderate unpleasant and unhealthy weather conditions hence called

“doctor winds”

With the aid of well labeled diagrams, explain how land and sea breezes occur(8) 2007

(1997)

Land and seas breezes refer to the general movement of air between the land

and the sea. Differential heating of land and water masses, which in turn

bring differences in terms of pressure, causes Land and sea breezes.

Differences in terms of pressure drive the wind in a particular direction.

A sea breeze happens during the day where by air moves from the sea to

develop a high pressure while the land a low pressure. Air then moves from

the sea which is a high-pressure area towards the land which is a low-

pressure area. The air on the land rises and moves upwards. Upon rising, it

meets colder layers in the upper atmosphere making the air to become cold

Page 108 of 159

too. This makes the rising air to decrease over the sea thereby completing a

circulation. The diagram below shows a sea breeze.

sun

Air decreasing

air rising

Low pressure sea breeze high pressure

Land

sea

A land breeze happens at night whereby the air moves from the land. Towards the

sea. This happens because at night, the land loses heat faster and become very cold,.

This makes the land to develop a high pressure. In contrast, the sea uses heat slowly

and at night becomes warm. This makes the sea to develop a low-pressure air then

moves from the land towards the sea. Air on the sea rises since it is warm after rising;

it meets colder upper atmospheric layers. Such rising air then becomes cold due to

decreasing temperatures in the air. Then the air becomes cold, heavier and descends

back to the land completing a circulation. The diagram below shows a land breeze

with the moon indicating that it happens at night.

Moon

Rising warm air

Decreasing cool air

land breeze

low pressure

Page 109 of 159

High pressure

Land

sea

Describe the influence of land and sea breezes on local weather.

- In summer seas, breezes have a cooling effect on coastal areas. This adds to

the attraction of the shore zone as a recreation facility.

- In the tropics, sea and land breezes can blow quiet strongly. Fishermen take

advantage of land breezes and sails out with them. They return the following

morning with the sea breezes, complete with their catch (fish)

With the aid of a diagram, explain how Chinook winds are formed

The Chinook winds originated from the Pacific ocean, ascends and descends the

Rockies mountain in Canada and the united states of America.

Windward leeward side

Pacific Ocean

As the wind ascends the Rockies, it brings heavy rainfall to the windward side which

faces the direction of the blowing Chinook winds.

Page 110 of 159

What influence do the Chinook winds have on the eastern foothills of the Rockies (3)

When descending the eastern part, the winds bring warm, raises temperature,

sometimes by 19

0

C in 15 minutes and therefore it is capable of melting and drying up

winter snow. This is why it is sometimes called “snow water”. It is thus of economics

value, especially in pastoral regions ranging from southern Colorado in the united

states to as far as Mackenzie River in Canada. The melting of the snow also help to

cultivate wheat in the Canadian Prairies.

The figure below shows the distribution of local winds. Study it and answer the

questions that follow

Name the local winds which blow in the area marked A, B, C, D, and E

A= Chinook

B= Harmattan

C= Fohn

D= Chiperon

Page 111 of 159

E= Santa Ana

On the same map insert an arrow indicating the direction of each of the local winds

On the map the arrow should point where the wind is going

How does the local wind which blow in an area marked D modify the weather of the

area

- It brings the persistent low clouds known as Stratus which can sometimes

bring drizzles or rain showers in the area especially the southern part.

- It makes temperatures to be very low in the area with chilly conditions

With the help of two examples explain why local winds are also called “doctor winds”

Some local winds moderate unpleasant and unhealthy weather conditions in the area

where the blow, hence doctor winds. Examples of such winds are the Harmattan

winds in West Africa from the Sahara desert. Although it is a hot, dry and dusty wind,

splitting tree trunks and damaging crops such as Cocoa in the northern part, the

Harmattan is called the doctor winds far Guinea coast. When it reaches Guinea

coast, it provides a welcome relief from the moist heat for it is a cool wind to that

area since it encourages evaporation hence cooling. Another example is the Chinook

winds. After descending the Rockies on the eastern side,it raises temperature by 19

0

C

in 15 minutes and melts and dries up winter snow. This has economic importance

especially in the pastoral regions strong Chinook winds makes winters to be mild and

pastures are available. Absence of Chinooks means a very cold winter and heavy

losses of livestock.

How are some local winds such as Fohn associated with avalanches

An avalanche is a mass of snow and ice which slides rapidly down the mountain slope

carrying with it thousands of tones of rocks. Local; winds such as Chinook when they

descend the leeward side, they raise temperatures by 8

0

C – 11

0

C. This makes snow to

be melted and start to move and become an avalanche.

What is the difference between anabatic winds and katabatic winds

Anabatic winds are winds from the valley upwards rising mountain slopes. This

happens when slopes are greatly heated by the sun making the air to move. In

contrast, katabatic winds are those that blow from higher to lower regions under the

influence of gravity e.g. Bora.

Page 112 of 159

Mention two positive impacts of the Chinook winds in the area where it exists

- It helps to bring rainfall to the western side of the Rockies as the winds from

eth Pacific rises the Rockies

- It helps to melt snow in the eastern side making pasture to grow for animals

grazing and for the cultivation of wheat.

Explain what causes chaperon winds

The chaperon wind is caused by the movement of the inter-tropical convergent zone

(ITCZ) to the northern hemisphere between May and August. As the wind moves to

the northern hemisphere, it deflects through Mozambique where it deflects through

Mozambique where it becomes Chiperon affecting mostly the southern part of Malawi

especially the Shire highlands composed of Blantyre, Thyolo and Mulanje.

How does chaperon winds affects Malawi

- It brings persistent low clouds known as status and drizzles or showers

especially in the shire highlands

- It lowers the temperature such that cold conditions are experienced

- It brings Mwera wind on Lake Malawi

What are the environmental importance of local winds

- They affect the movement of pollutants such as pollution fumes far away from

their sources.

- They moderate unpleasant and unhealthy weather conditions. For examples,

they help to bring rainfall help to melt snow, thus being called “doctor winds”

- They exert a powerful stress on animals and plants, depending on whether

they are dry and extremely hot or cold.

What are the two differences between local winds and prevailing winds

- Local winds are caused by the immediate influences of the surrounding

topography or relief while prevailing winds are mainly caused by large scale

global pressure systems

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- Local winds affect small area while prevailing winds affect very large areas.

- Local winds are named after the local names in areas, which they exist while

as prevailing winds, have global names such as trade winds, wetserlies and

polar winds.

CYCLONES AND ANTICYCLONES

What is a cyclone 92006)

A system of wind rotating around a center of low pressure, turning clockwise in the southern

hemisphere and anticlockwise in the northern hemisphere.

Name two types of cyclones (2000)

a. Temperate cyclones also known as depressions

b. Tropical cyclones

Explain two differences between depressions and tropical cyclones

- A tropical cyclone usually occurs in the tropics within the belt of trade winds

while as a depression occurs in the temperate regions within the belt of

Weatherly winds

- A tropical cyclone is smaller in size while as a depression is larger in size

- A tropical cyclone is more violent accompanied by very strong winds as

compared to a depression.

Using a well a labeled diagram, explain the direction of wind in a cyclone in the

siouthern hemisphere (2000)

A cyclone is a storm generated by a low atmosphere pressure system at the center. The

isobars are closely spaced and the form a circular shape. As the low pressure is at the centre

and high pressure outwards, winds move from outside which is a high pressure region to

inside which is a low pressure region. The wind when going inside deflects to the lefthand

side as it is in the southern hemisphere. As the coriolis force is in effect. This deflection

makes the general circulation of air to be in a clock wise direction in the southern

hemisphere.

Diagram

Give two conditions necessary for the development of a tropical cyclone

- Air must be blowing inwards towards the center and rising rapidly and

nimbostartyuis clouds must form to give heavy rains.

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- There must be an inward flow of air in the upper level of the atmosphere

- An abundant source of warm, moist air of temperature of about 27

0

C near to

the sea surface.

Why is it that cyclones do not develop in the regions between 0

0

and 5

0

N or S of the

equator

Within 0

0

and 5

0

North or South of the equator, the coriolis force is very weak. This makes the

deflection of winds to be weak also . as a result, it is very difficult for winds to circulate ior

swirl around a low pressure center in order to give rise to a cyclone

Give two similarities between a tropical cyclone and a depression

a. They both circulate in an anticlockwise direction in nthe northern

hemispjhere and clockwise direction in the southern hemeisphere

b. They both have a low pressure at the center with air moving from

outside to inside

State two general characteristics of tropical cyclones

a. It originates over oceans and moves towards the landmasses

b. Does not occur in the regions within about 5

0

of the equator due to weak coriolis force

c. The rotaion is clockwise in the siouthern hemisphere and anticlockwise in the

northern hemisphere

d. It is smaller than a depression

Study the figure below which shows the circulatory pattern of winds in a cyclone and

answer the questions that follow:

Diagrams

Which of these diagrams represent wind patterns in a cyclone

It is A and B

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Give a reason for your answer

The general circulation of air in a cyclone is in an anticlockwise direction in the northern

hemisphere which is shown in A and in a clockwise direction in the southern hemisphere

which is shown in B

Which of the diagram represent wind patterns in an anticyclone

It is C and D

Give a reason for your answer

The general circulation of air is in a clockwise direction in the northern hemisphere. This is

shown in C and anticlockwise direction in the southern hemisphere which is shown in D.

Hurricanes often occur in the summer in the West Indies. Similar tropical cyclones also

develop in other parts of the world. Name three other regions where they occur and say

what names are given to these cyclones.

- In Australia they are called Willy-Willies

- In Madagascar they are called Cyclones

- In India around the Indian Ocean are called Cyclones

- In the China sea and around Japan in Asia they are called Typhoons

Explain the development of a tropical cyclone

Tropical cyclones develop in the tropics within the belt of trade winds. These develop when

Noprth East trade winds and south east trade meet along the inter- tropical front. Where they

meet, one is uplifted over the other and its moisture produces heavy rainfall. These develop

over oceans because air masses which have travelled over oceans have warm moist lower

layer. The tropical cyclones die out when reaching the land because their supply of moist air

is cut off completely.

Describe the weather associated with a tropical cyclone

- Development of gusty winds and thick clouds especially with the arrival of the

vortex

- Very violent winds accompanied by heavy rainfall that often results into

floods

- Calm conditions with the return of the eye

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The figure below shows a section through tropical cyclone

Diagram

What different weather conditions can be noticed in A and B

In A which is anneye clam conditions are experienced. This is because the sea has low

p[ressure. In B which is the vortex, violent conditions with very strong winds can be noticed.

This is because this is the are where the air rises as it moves on both sides towards the center.

The figure below shows the movement of a cyclone. Study it and answer the questions which

follow

Diagrams

Describe how weather would change at X if the cyclone passed through the place (2000)

(6 marks)

In stage A, the cyclone has not yet reached a place. Therefore at X the sky will be clear with

some wispy cirrus clouds. The wind blows from south east.

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In stage B, the warm front has just passed through the place X such that the place is between

the cold front and the warm front. Wind changes direction from south east to south west.

Temperature also rises as the place lies in the warm sector.

In stage C, which is the last, a cyclone has passed through a place. The place experiences

some rain showers, the sky then clears as the wind blows from northwest.

What is the direction of wind at stage B

The wind changes direction from south east to South west.

Draw map of the world on this map show and name the following: Willy willies,

Typhoons, Hurricanes and cyclones

When answering this question it is important tom know where these tropical cyclones are

found. It is important to start such a question in this way:

The Willy willies, typhoons, the cyclones, hurricanes are all the tropical cyclones existing in

the belt of trade winds. They are known by different names in areas where they are found.

The Willy willies exist off the coast of Queensland or Australia, the Hurricanes, in the

Caribbean in west indies, typhoons in China sea in Asia and the cyclones off the coast of

Madagascar and India.

Explain why anticyclones are associated with the following weather conditions:-

a. Dry conditions

This is because the descending air is warmed up as air pressure increases near the surface.

The air does not contain moisture for condensation and precipitation to take place.

b. Little wind with little force

There is low pressure gradient showing that there is little difference in pressure over a wide

are

c. Hot and sunny conditions

Long hours of daylight during which the sun shines from cloudless skies. The sun is also at a

high angle in the sky for greater insolation.

d. Cold days in winter

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Short hours of daylight from the weak winter sun shines from a low angle in the sky and

insolation roles are low.

e. Frost especially on winter nights

Clear skies allow heat loss from the ground surface. At night, moisture in contact with the

cold ground surface condenses into ice when thetemperature falls below freezing point.

f. Fog mainly in winter

Clear skies allow heat loss from the ground surface at night; moisture in the air in contact

with the cold ground surface condenses droplets of water form around tiny dust particles in

the air which reduce visibility. This is what is called fog.

COMBINTION QUESTIONS

Explain the meaning of the following geographical terms:-

(a) Convectional rainfall

This is the type of rainfall which is characterized by thunder, lightning and anvil shaped

clouds. It is accom[panied by the rising heated air. The air rises inform of convection

currents. The heated air rises with moisture which eventually cools to form big

cumulonimbus anvil shaped clouds which then brings heavy rainfall especially in the

afternoon.

(b) Land and sea breezes

These involve the circulation of the air between the land and the sea depending on the

position of high and low pressure.

(c) International date lines:

This refers to a line at which the day is either lost or gained when crossed. It follows the

longitude 180

0

east or west of the prime meridian.

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(d) Tropical cyclone

This is a storm generated by a low atmosphere pressure system of air in which iisobars on the

paper are circular in shape.

Explain why the following occur:

a. Tropical thunderstorms occur in the late afternoons

This happens because for tropical thunderstorms to occur it is as a result of intense heating of

land and water masses by the solar energy in the morning hours. By the afternoon hours air

with moisture has already risen. This contributes to thunderstorms especially in the tropics.

b. Rainfall is usually unevenly distributed over barriers

This is because mountains act as stumbling block to the winds that blow towards them from

the oceans seas or lakes. This is very common in places where on-shore winds rise up over

hilly or mountain regions lying at right angles to the direction of the wind. This contributes to

unevenly distributed rainfall because rainfall usually falls and the wind side. This is the side

of a mountain that faces the direction of the moist winds. In contrast, the leeward side

receives very little or no rainfall at all. This is because this side face away from the moist

laden winds such that when the winds descend these mountain slopes they are cool and dry

without moisture hence little or no rainfall.

c. The Mediterranean lowlands receive rainfall only in winter

This happens because the trade winds that blow in summer are off-shore. These are dry and

give no rains. Rainfall is received in winter, because the on-shore westerly winds blow in

winter. These since they are on-shore, they are moist laden and bring heavy cyclonic rainfall.

d. More rain falls in west Africa between 1

st

May and 31

st

October than 1

st

Novermber and 30

th

april

This happens because between 1

st

May and 31

st

October the area comes under the influence

of a low pressure belt. This happens because the sun appears to be overhead in the area.

There is intense heating which reduces the pressure. Air then converge in the area such air

masses bring heavy rainfall. The place cannot experience more rainfall between 1

st

November

and 30

th

April because iot develops a high pressure. This is as a result of the sun being far

from the area. This leads to no rsinfall because air moves out of the region.

Carefully explain the meaning of the following:

a. Sea breezes are day winds and land breezes are night winds

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Sea breeze deals with the circulation of air from the sea to the land. This happens because

there is a high pressure developed over the sea as the sea absorbhs heat slowly while there is

a low pressure over the land as the land absorbs heat faster. Air then moves from the sea

towards the land. It is known as day winds because the movement of air form the sea towards

the land happens during the day time. In sa land breeze air moves from the land to the sea.

This happenes because the land develops a high pressure after losing heat faster whuile the

sea develops a low pressure after losing the heat slowly. Land breezes are known as night

winds because the circulation of air from the land towards the sea happens at night.

b. Water surfaces gain and lose heat more slowly than land surfaces

Water is transparent and sun rays penetrate more deeply than they can on the land. In

addition, more energy is required to heat a given amount of water than the same amount of

soil due to the fact that the molecules of soil are closely arranged than those of water.

Moreover, water moves which makes the heat to be distributed than the land which does not

move. For these reasons, the land absorbs heat fatser than water but the land also loses the

heat absorbed afster than water.

c. Temperature decreases as altitude increases.

Low altitudes such as along the sea shores the temperature is high and the weather is warm

while high altitude areas such as on ttop of the mountain, the temperatures is lower and the

weather is cool. Temperature really decreases with an increase in altitude as noticed above

because, in low altitude are the air is thisck and conatins a lot of dust particles and water

vapor. These makes the heat from the earth’s surface to pass rapidly making the temperature

to decrease and the weather to be cool. Thus temperature drops at the rate of 6.4

0

C for every

1000m rise in altitude.

Diagram

Draw a map of the world. On it shade and write with the letters

Page 121 of 159

a. TC over an area affect by tropical cyclones

b. SW over a coastal area that experiences the Souith- westerlies

c. RA over an area in Africa that has rainfall throughout the year

d. MW over an area found in the southern hemisphere that has mild and wet

winter, warm and dry summers.

e. DR over an area with a great diurnal range of temperature.

Diagram

KEY

TC= tropical cyclones

SW= south westerly

RA= Rainfall throughout the year

DR= great diurnal ranmge of temeoprature

MW= mild and wet winters, warm and dry summers

NOTE:

TC areas experiencing Tropical cyclones. These should include areas where the cyclones,

typhoons, willy willies and hurricanes are found.

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RA rainfall throughout the year refers to an area with an equatorial climate

DR an area with agreat diurnal temperature range is a place such as any desert like Sahara,

Kalahari

MW a place that has mild and wet winters, warm and dry summers refers to a place with the

Mediterranean climate

Explain why:

a. The Sahara desert does not experience much rainfall

- It lies outside the subtropical high pressure belt area. This area is not

associated with rainfall because the air is descending, and such descending air

is cool and dry without moisture, a condition not favourable for precipitation.

- The rain bearing trade winds are off-shore and the westerlies that are on-shore

blow outside the desert limits, a condition which is not associated with heavy

rainfall.

- It is affected by the canaries’ cold ocean currents. This ocean current, being

cold does not bring precipitation to the area as it does not absorb moisture.

b. The mid-latitudes experience cyclonic rainfall

Cyclonic rainfall is the type of rainfall which is formed when two air masses

of different temperatures, that is, one warm and the other cold, meet. The

result of this meeting is that warm air rises up over the cold air mass and it

cools gradually to form a cloud which consequently brings about rainfall. This

rainfall is experienced in the mid-latitudes because in such an area is where

warm air from the low latitudes meets cold air from the high latitudes

creating a boundary cold front, hence this rainfall also being called frontal.

Explain the following:

a. Extreme temperatures are experienced in the interior of

temperature continents

Such place are in the interioirs of continents such as North America, South

America and Uresia. These place such as Saskatchewan in North America

experience extreme temperatures because they are far from the coast. The

warming influence of the oceans doesnmot reach them. In fact when warm

winds blow across the oceans, by the time such warm winds reach such

interiors, they are very cool and dry which makes temperature to be very

low.

b. The west coasts of the Southern continents roughly between

latitudes 15

0

to 30

0

are extreme dry.

Page 123 of 159

- Such areas are affected by the cold ocean currents. These do not bring

precipitation because they are already dry and do not absorb moisture which

can result into heavy rainfall.

- Such places experience off shore trade winds which cannot bring rainfall as

the winds move out of the land. The descending air that follows is just very

warm and dry, a condition that cannot bring precipitation.

Diagram

Explain one reason why the region marked X receives little rain

- Its located in land maked it to be on the leeward side from the coastal

monsoon rains, hence little rainfall

- Located in an area where the winds are off-shore. The place is located along a

horse latitude high pressure belt which send the winds out of the area. This

makes the area to be dry as such winds do not bring precipitation.

Explain two reasons why winters are bitterly cold in the region marked B than that

marked A

- The region marked A in winter has a warming influence from the sea. This

happens because the sea loses heat slowly than the land such that in winter, the

area marked B has severely winters as it is far from the warming influence of

the sea as compared to A. in other words, in winter the land loses the heat

faster which makes B to experience severe winters as it is inland.

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- The place marked A is influenced by the North Pacific warm Ocean current.

This helps to raise the temperatures of A. this warming influence decreases

when going inland. This makes B to experience very cold conditions.

State two ocean currents which meet at the point marked M

- The north Atlantic Drift warm ocean current

- The cold Labrador ocean current

Explain the presence of fog in the area labeled N. give one point

Due to the flow of the Benguela cold ocean current which meets some

warm air.This results into fog formation.

Explain one reason why diurnal temperature range is very high in the region labeled D

During the day, the sky is not covered with a lot of clouds. This makes

temperatures to increase as a lot of sun rays reach the surface of the earth

since it is a desert area. At night heat easily escapes as the sky is also not

covered with cloud. This makes temperatures to be very low at night. The

difference between day temperatures and night temperatures become very

large, hence high diurnal temperature range.

Explain why vegetation of the region labeled K is dominated by mosses and linches

The place experience very low temperatures which makes soil to be frozen

for most parts of the year. This makes vegetation not to grow apart from

simple linches and mosses with stunted growth.

CLIMATE AND VEGETATION

Study the data below which shows the climatic statistics for a certain station and answer

the questions that follow

Table

Page 125 of 159

Identify the type of climate for the station

It is a tropical continental or Sudan type of climate

Where is this type of climate developed?

Within the tropics between 5

0

and 15

0

North and South of the equator.

Describe any two characteristics of this climate

- Summers are hot with temperatures around 32

0

C. Winters are cooler, with an

annual temperature range of between 8

0C

and 11

0

C.

- Heavy convectional rainfall in summer while winters are usually dry

- Annual rainfall of between 762 mm and 850 mm

- In the northern hemisphere the hot rainy season is usually from May to

October. The rest of the year is cool and dry. In the southern hemisphere the

hot rainy season is from November to April and the rest of the year is cool

and dry.

Explain any two factors which hinder economic development in the region

- The unreliable rainfall bringing about drought conditions bring

famine to the area.

- Heavy summer rainfall results into heavy leaching of minerals. This

does not only result into loss of soil fertility but also the formation of

poor lateritic soils.

- Diseases and pests such as tsetse flies which do not favour animal

rearing

- Poor communication in this climate

What type of vegetation is associated with this type of climate?

It is the tropical savanna vegetation

Give three characteristics of this kind of vegetation

- It has tall grass with scattered trees

- The trees are deciduous, that is they shed their leaves during drier

parts of the year.

- Trees have long roots

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- Most trees are umbrella in shape while some have thick trunks

- The grass dries up or remains dormant during the hot dry season

Give three examples of the trees found in this type of climate

- Baobao trees

- Palms

- Acacias

- Gum trees

- Elephant grass

Describe some characteristic features of some of the above vegetation that makes it to

survive in this climate.

- Baobab- it has a very thick trunk. This is used for storing water

during the rainy season. This stored water is used during the hot and

dry season when the climate does not receive rainfall. It also shed

some leaves during the hot dry season in order to reduce the excessive

loss of water through transpiration

- Acacias- the trees are umbrella shaped that help to protect the roots

from dryness. They have deep roots that get water from the lower

horizons of the soil. They shed their leaves in hot, dry season in order

to reduce transpiration

- Elephant grass: remains dormant by drying up in the hot dry season.

It is also very tough and resistant to excessive transportation.

Table

Study the climatic statistics for a certain station below and answer the questions that

follow

Page 127 of 159

Identify the type of climate for the station

It is the warm temperature western margin also called the Mediterranean climate.

List any three characteristics of this type of climate

- It is a unique type of climate because it receives rainfall in winter

when the westerly winds blow on shore

- Off-shore trade winds blow in summer. These are dry and give no

rains

- Temperature range from 21

0

C in summer to10

0

C or below in winter

- Receive local winds like Sirocco, Mistral, Bora

- The annual rainfall ranges from 500mm to 760 mm. it rarely reaches

840mm

In which hemisphere is the station located and gives a reason for your answer

It is in the northern hemisphere. This is because the climates receive rainfall in

winter as a result of the on shore westerly. According to the table, the station

receives rainfall from November, December, and January to February. During

these months it is winter in the northern hemisphere as during the sametime it

is summer in the southern hemisphere. During this time the sun appears to be

overhead along the tropics of Capricorn in the southern hemisphere which then

experiences summer. This means the northern hemisphere is in winter.

Suggest any two important agricultural activities or developments in this station.

- the region is important for fruit farming such as oranges, lemos, grapes and limes

- The region produce cereals such as wheat and barley

- The region produces vegetables

- The mountain pastures support sheep, goats and cattle

Give three examples of important industries that can be developed in this region

- Wine making industry due to the growing of grapes (viticulture) which are used in

wine production.

- Flour milling due to the growing of barley and wheat. The flour is used for baking

- Fruit canning industry due to the growing of citrus fruits such as oranges and lemons

- Tourism industry since summer is warm and bright and winters are so mild and cool.

Page 128 of 159

Study the climatic statistics of the table below for certain station

Table

Identify the type of climate for the station

It is the equatorial climate

Calculate the temperature range for the station

26

0

C – 23

0

C = 3

0

C

Describe any four characteristics of this type of climate

- Heavy well distributed convectional rainfall of up to 2000mm annually. Rainfall

comes in the afternoon accompanied by thunder and lightning.

- There are no definite seasons because there is heavy rainfall and high temperatures

throughout the year as a result of the low pressure in region.

- Small temperature range of between 1

0

C and 3

0

C with 26

0

C as the average daily

temperatures.

- Humidity is always high.

Explain any two factors that hinder economic development in the region

- Excessive heat and high humidity affects the health of people negatively

- Prevalence of bacteria and insects pests such as tsetse flies. These attack people,

animals and crops.

- Thickness of the vegetation makes clearing of the communication difficult and

maintenance of the land difficult

- Due to heavy rainfall, there is rapid deterioration of the soil through leaching.

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Give three examples of areas with such a climate

- The Amazon basin

- The Congo basin

- Guinea coast

- Philippines

- Indonesia

- Malaysia

What type of vegetation is associated with this type of climate?

It is tropical evergreen or rainforests vegetation

Describe any two characteristics features of this type of vegetation named above

- Contains a great variety of plants with thick vegetation.

- Trees are very tall with buttress roots forming a canopy which results into little

undergrowth

- There is continuous growth of trees, that is, flowering, fruiting and shedding take

place throughout the year.

- Most of the trees have broad leaves with luxurious growth

- Most trees are evergreen.

Give two examples of trees that are found in this vegetation

- Mahogany

- Ebony

- Rosewood

- Iron wood

- Greenheart

- Orchids

Of what two uses can be the trees named above

- Used for lumbering e.g. mahogany

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- Used for sculpture e.g. ebony

- Used for poles

Study the tables A and B below which show the climate for two stations (1995)

Table

Suggest a climate region for each of the weather stations

- Station A: hot equatorial climate

- Station B: hot tropical desert climate

State three differences of the climates of the weather stations (6 marks)

- Station A receives heavy rainfall, well distributed throughout the year while as station

B receives very little rainfall, with some months being completely dry

- Station A is located in the southern hemisphere as it receives higher rainfall from

November to March while station B is in the northern because the little rainfall it

receives is in June, July and august.

- Station A has a very small temperature range of 1

0

C while station B has a large

temperature range of 12

0

C

What type of rainfall is most likely to be experienced at both stations

Convectional rainfall, as a result of the heating and rising of air as a result of a low

pressure.

Explain three ways in which the vegetation found at station B has adapted to the

climatic conditions of the area (6 marks)

- They have thick leaves and sterms to store water to be during driest months

- Have waxy leaves that prevent transpiration and also have tiny leaves

- They produce sleepy seeds which lie dormant when it is very dry and germinate when

the water is available

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- They grow roots that get to the depth to get water from the lower horizons of the soil

Give two examples of the vegetation found in station B

- Cacti

- Thorn bushes

- Date palms

Draw a diagrammatic representation of the type of vegetation that could be found in the

climatic region of station A

Trees are very close and they are usually tall. The vegetation occurs in layers, upper

layer, middle layer and the bottom layer. Since the vegetation forms a canopy,

climbing plants such as lianas found their way to the top by climbing tall trees in

search of sunlight. The tall trees are supported by buttress roots.

Diagram

Describe any three factors that could pose problems in the economic development of the

region in which station A is found (6 Marks)

- Prevalence of pests and diseases. These attack people, animals and crops

- Heavy rainfall result s into poor soils as a result of leaching

- Construction of roads is difficult due to problems in clearing the thick forests

Name the two areas, one in North America and one in South America, that have a

Mediterranean type of climate (2 marks)

North America: California

South America: central Chile

Map

Page 132 of 159

Explain and account for the following

The western margin of the northern continents between 30

0

N and 45

0

N receive most of

the rain from on shore winds in winter

The western margin of the continents between 30

0

n and 45

0

N experience the

Mediterranean type of climate. This is the only climate which receives rain in

winter. This happens because the trade wind s that blow in summer are off-

shore and very dry. Such trade winds do not bring rainfall. Rainfall is brought

in winter when the westerly winds are on-shore. This makes the area to receive

rainfall in winter 0n-shore westerly winds.

The diurnal temperature range in the Sahara deserts is very large

The Sahara desert experience very high temperatures during the day. This is

because the sky is short cloudless. This allows all the sunlight rays to reach the

earth’s surface without being obstructed which in turn makes temperatures to

be high. At night the temperatures are very low and the weather is cool. This is

because at night the heat that was absorbed escapes into the atmosphere easily.

This is because at night the area is cloudless. The diurnal temperature refers to

the temperatures of the day. Such a difference becomes large in the Sahara

desert because day temperatures are very low. For example, the day

temperature may reach 29

0

C while night temperatures may reach 10

0

C. The

difference 29

0

C – 10

0

C = 19

0

C is large.

Explain and account for the following

Hot deserts are usually located on the western deserts are usually on the western sides

of the continents.

Desserts are region characterized by aridity and poor soils, due to the fact that

precipitation is not only scarce but also rare. Such places are locate on the

western sides of the continents because in such western sides is where most of

cold ocean currents exist. Such cold ocean currents are responsible for the

existence of such deserts because the cold ocean currents are dry without

moisture. With this they do not bring precipitation to such western sides of the

continents, making such continents to be characterized by aridity. For

Page 133 of 159

example, the California cold current is responsible for the formation of the

California desert, the Peruvian for the Atacama desert, both on the western

side of the North America and South America respectively.

Name:

i. A region where rain falls all the year

Amazon basin, congo basin, Malaysia,Indonesia, guinea coast.

ii. A region where rain from June to September only

Ethiopia, sudan

iii. A region where rain rarely falls

Sahara desert, Kalahari Desert, Atacama Desert

Draw an outline of map of South America and on it shade and name:-

a. One region having an equatorial climate

b. One region having a Mediterranean climate

c. One region having a savanna climate

In South America the area which has equatorial climate is the Amazon basin, the

central Chile has the Mediterranean while Venezuela and Brazil have the Savanna

climate. This map below shows these places.

Map

Explain the following using relevant diagrams and sketch maps where possible

The sahara desert receiving little or no rain

The Sahara desert lies along the subtropical high pressure. It therefore

experiences off-shore trade winds which are dry and do not bring

precipitation. In addition, the area is affected by the canaries’ cold ocean

current. Being a cold ocean current, it is dry without moisture and results

into no rainfall upon reaching the area. The sketch map below shows this.

Map

Page 134 of 159

Regions bordering the equatorial zone of Africa receive most of the rain throughout the

year

Equatorial areas are those located between 0

0

and 5

0

north and south of the

equator. This are really receives rainfall throughout the year. This is

because the area experiences very high temperatures as a result of the sun

striking the region at an angle of 90

0

. This high temperature makes

pressure to be reduced. Thus the region experiences low pressure. This in

turn makes the wind from the subtropical.

Desert plants are able to survive for long periods without water

Since deserts receive very little or no rainfall at all for a large part of the

year, it is difficult for vegetation to grow as it is with some other climates.

These desert plants that grow and survive have special characteristics that

make them to survive. Such characteristics include developing long roots

that take water at depth, have few or no leaves at all in order to survive and

reduce the rate of transpiration, have thick trunks with succulent stems that

help to keep water that is used during the critical driest months. In

addition, the plants produce sleepy seeds that remain dormant during the

dry months until little amount of water is when such seeds germinate.

Heavy fog frequently occurs over the waters around New Founder land

Fog usually forms when there is a meeting of a cold and warm ocean

current. Fogs are therefore frequently formed in the New Founderland

because of the meeting of the Labrador and east Greenland cold ocean

currents with the North Atlantic warm ocean current.

Give three differences between the equatorial vegetation and the Savanna vegetation

- Equatorial vegetation or tropical rainforest has a continuous canopy while the savanna

does not form a canopy because it has a lot of grass which is spiced by trees.

- Equatorial vegetation is dominated by very big trees while savanna vegetation is

dominated by grass of about 2m tall.

- Growth, flowering and fruiting of trees is there all the time in the equatorial while

savanna it is seasonal, especially in warm wet season.

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- Trees in equatorial are evergreen while in savanna it is deciduous.

State two differences between an equatorial rainforest and a tropical monsoon forest

(1986)

- Tropical rainforest vegetation has large numbers of species while in monsoon forest

the species of animals and plants are in small numbers.

- Most of the trees in tropical monsoon forests are deciduous while most of the trees in

the tropical rainforest are evergreen

- In tropical monsoon trees are at least sparsely spread while in the tropical rainforest

trees are closely spaced

- In tropical rainforest vegetation, there is complete canopy.this makes little under

growth while as in the tropical monsoon, there is denser underground because

sunlight is able to reach the ground.

Explain why there is a difference in vegetation between the two (2) 1986

This is due to their differences in latitudinal location of the two areas, which in

turn makes the two places to have differences in terms of temperature and rainfall.

The equatorial vegetation is located in the region with high temperatures and

rainfall throughout the year while as that of the monsoon receives most of the

rains in summer when monsoon winds blow towards the area with winters being

dry.

Why do both types of vegetation have tall trees? (1989)

Both are located within the tropics with higher temperatures and a lot of rainfall

even if in the monsoon heavy rainfall is in summer. This makes trees to grow very

tall.

Name three trees of commercial value found in each of the following:

Equatorial

- Mahogany, iron wood, rose wood, ebony and green heart

Tropical monsoon forest

- Teak, bamboo, Sal, sandal wood, eucalyptus and acacia

Coniferous forest

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- Hemlock, spruce, pine and fir

The figure below shows map of Africa showing two different climatic regions. Use it

to answer the questions that follow (2006)

Map

Identify the type of climate that is experienced in regions marked A and B

A= equatorial climate

B= tropical continental climate

Explain why the region marked B experiences rain from November to March and no

rain from May to September (6 marks)

The region marked B is in the southern hemisphere. It receives rain in warm wet

season as a result of the increase in the solar radiation which in turn makes

pressure to be reduced. When pressure is low, winds from high pressure areas

especially in oceans converge in the region. Such winds upon crossing the seas

collect moisture which results into heavy rainfall. The mentioned areas receive

rain form November to March because during this period the sun appears to be

overhead in southern hemisphere over the tropic of Capricorn. This increases solar

radiation and reduces pressure. Winds such as the south east trades, the north east

trades and the congo air mass converge in the area. These results into heavy

rainfall with the moisture collected. The area develops high pressure from May to

September when the sun appears to be drifting to the northern hemisphere making

the area to have off shore winds which are dry hence no rainfall between May and

September.

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Name the deserts labeled C and D

C= Sahara

D= Kalahari Desert

Explain two reasons why the deserts labeled C and D are dry

Influenced by the cold ocean currents which do not bring precipitation to

such areas as the currents themselves are dry without moisture. For

example C is influenced by the canaries cold current while D is influenced

by the benguela ocean current.

The places experience the off shore winds as they lie within the horse

latitude high pressure belts. Such winds are dry and do not bring

precipitation to the areas hence dry places.

Explain why desert plants have each of the following characteristics:

Long and well spaced out roots

Such long roots help to get water from the lower horizons of th earth with

the well spaced out roots searching water as the palces are very arid with

shortage of moisture for plants to grow.

Few or no leaves at all

This help to reduce the excessive loss of water through transpiration as

water is scarce in deserts. Having many leaves would encourage and

increase the rate of transpiration which would make the plants to wilt as

moisture is not enough.

Thick succulent storms

These help to keep water which is used during the drier months when there

is a great need for this water.

Study map of the world below and answer the questions that follow 91992)

Map

Page 138 of 159

Explain why:-

The are marked A experiences heavy rains in the months May to August (2 marks)

This area between May and August comes under the influence of the

monsoon winds. Such winds blow on shore form the Indian Ocean. It

happens because the sun appears to be overhead in the area, which make

temperature makes pressure to decrease in area while over the oceans the

pressure is high. Wind blow towards the area carrying moisture that results

into heavy rainfall upon reaching the land.

The area marked B receives rainfall throughout the year

It is under the influence of the north Atlantic drift ocean current. Being a

warm current bring moisture to the area which results into heavy rainfall.

The coastline marked C has ice-bound harbours in winter while that of D is ice-free

The coastline marked C is influenced by a cold ocean current known as

Labrador. This lowers the temperature in the area which contributes to the

existence of the ice. This is in contrast with the coastline marked D which

is influenced by the North Pacific warm ocean current. Being a warm

ocean current it melts the ice in the area thereby making it to be ice free.

The coastline marked E receives less than 250 mm of rain per annum

This area is influenced by a cold Peruvian ocean current. Being a cold

ocean current it is dry and when it reaches the area, it does not result into a

lot of rainfall hence 250mm per annum.

Day temperatures in the area marked F are much higher than those in G

During the day time, the place marked F does not have a lot of clouds.

This allows a lot of sunlight energy to reaching the earth’s surface which

increases temperatures. This is in contrast to the place marked G which is

covered with a lot of clouds during the day. Such clouds reflect some of

the sunlight rays back to the atmosphere. This consequently lowers the

temperature during the day.

The area marked H experiences winter rains

Page 139 of 159

The place experiences off-shore trade winds during summer. This makes

the area not to receive rainfall in summer as it is the case with some other

areas. In winter the place experiences on-shore westerly winds. These

being on-shore bring a lot of rainfall to the area. Consequently the area

experiences winter rains as a result of on-shore westerly winds.

Identify the type of climate found in the region marked S

This is the tropical continental climate also called tropical Sudan climate

Explain three ways in which the climate and vegetation of the area marked S is

economically important, give one example drawn from Africa in each case.

- The climate favors the cultivation of plantation crops. For instance, the tea plantations

in Malawi

- In some places, pastoralist is done especially in east Africa. For example the Masai

tribe in Kenya and Tanzania

- It is a home of wild animals that is, it is also called a “big game country”, with the

herbivores and carnivores dominating. This makes the area as a center of tourism.

Thus, the place has a many national parks and game reserves like those in Malawi.

Explain three ways in which the physical environment of the area marked S limits

economic development

- frequent drought is a serious problem which leads to shortage of water and famine

- torrential down pours of heavy rains cause leaching making the soil to lose fertility

- Existence of tropical diseases and pests such as tsetse flies that hamper animal

farming.

Study the climatic statistics below for a certain station and answer the questions that

follow:

Table

Suggest the type of climate for the station

Page 140 of 159

Tundra climate

Calculate the temperature range for the station

8

0

C - -40

0

C = 48

0

C

Describe any our characteristics of this type of climate

- the average temperature of the warmest month is below 10

0

C but above 0

0

C and

temperature for the coldest month is between -29

0

C and -40

0

C

- large annual temp[erature of up to 50

0

C

- total annual precipitation is above 250mm

- Winters are long and severe with short warm summers. Winter nights are long with

hardly any day light and summer days are long with hardly any night

- glei soils are main features of Tundra. These soils are formed under the influence poor

drainage

Give three chief features of the vegetation found in this climate

- it has a variety of grass grows together with mosses, linches and flowring plnts such

as bilberry and bearberry

- the grasses rea short due to slow growth because of the very cold climate

- the grass is punctuated by very stunted growth of bushes

Describe any agricultural development associated with this type of climate that you

know

Agricultural development is difficult because temperatures become very low such

that the sub soil is permanently frozen (perma-frost)

Give two reasons that make the climate not to favour tall trees

- strong and intensely cold winds of winter make normal tree growth impossible

- The soils are permanently frozen.

Why is it that this climate is only found in the northern hemisphere?

This is because the northern hemisphere has a large land mass than the southern

hemisphere which s mainly made up of water.

What do you understand by the term solifluction

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This is a process through which a thick mud of melting water that flow down

slope without breaking. On the surface is produced in the cold climates such as

tundra.

Study the climatic data below and answer the questions that follow

Table

What name is given to the type of climate named above

It is cool temperate continental also called Siberian climate

Calculate the annual temperature range for the climate named above

20

0

C - -19

0

C = 39

0

c

Give three characteristics of this climate named above

- Precipitation varies between 380mm and 635mm well distributed throughout the year

with maximum in summer

- The annual temperature range is large such that sometimes it is more than 30

0

C

- Bitterly cold winter of long duration and cool brief summer

- In winter the temperatures are so low that heavy snowfall is common, and rivers are

frozen

- The highest temperatures are above 10

0

C but below or around 20

0

C.

Give two examples of countries with the climate named above

- Canada

- Union of soviet socialist republic (USSR) or common wealth of independent states

(CIS) which were former Russian colonies

Page 142 of 159

NOTE:- the climate is experienced only in the northern hemisphere from Alaska to

Hudson Bay and from Sweden to Kamchatka Peninsula, with 60

0

N as the outer limit.

What name is given to the vegetation found in the climate named above

Evergreen coniferous forest

Give three characteristics of the vegetation found in the climate named above

- Almost all conifers are evergreen

- The leaves are small, thick, leathery and needle –shaped to check excessive

transpiration

- There is very little undergrowth

- Are conically shaped to survive the subarctic climate

- Trees grow at reasonable slow rate

- Trees have big area or mass of wood than leaves

Give two important activities done by the people in this climate shown above

- Lumbering as the most important activity. This is because the vegetation is mainly

made up of soft wood

- Animal trapping as the climate has many fur-bearing animals such as the mink,

beaver, muskrat, ermine and silver fox. These animals are hunted for fur.

Give three examples of trees that are found in the vegetation of climate named above

- Hemlock

- Pine

- Fir

- Spruce

- Larch

Give three examples of industries with their products that can be developed in this

climate

- Saw milling industry, producing timber plywood, planks and hard boards

- Paper and pulp industry, producing paper, notebooks, very famous in the united states

of America

- Fuel industry in which the soft wood is burnt as fuel for heating and cooking

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- Industrial raw materials such as matches. Furniture, wood curvings, toys, crates and

packing cases. The by-products of timber are used for making rayon, dyes, cosmetics,

turpentine, varnishes and liquid resins.

Study the photographs of the vegetation types below and answer the questions atht

follow (1997)

Photos

Take not of the letters

Name the vegetation type shown by each photograph

- Tropical rainforest vegetation

- Temperate grassland

Suggest two countries outside Africa where each of the vegetation types is found

Amazon, phillipines, Indonesia, Malaysia, Australia.

NOTE: if the question would require examples from Africa

Congo, guinea coast

Mention two areas in Malawi where the vegetation type shown by figure A is found

- Nkhata Bay

- Mulanje

- Thyolo

Give two resons why the areas mentioned in the above are ideal for the growth of

vegetation type A

- Such areas receive heavy rainfall well distributed that favours the growth of the

vegetation.

- Experience high temperatures which favour the growth of the vegetation

From the evidence provided by the photographs:

What is the economic importance of the vegetation shown in B

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- As it is treeless with very flat land, it can easily be used for the cultivation of cereal

such as wheat in the prairies.

- Due to its flatness and as the fact that there tall grass, it is used for ranching such as

cattle ranching in Argentina.

What are the two main characteristics of the vegetation type shown in B (2)

- Extensive area of grass without trees

- Grass occurs together with herds

- The grass becomes short moving towards the temperate desert areas

Give three factors which hinder agricultural developments in A

- Since it is densely forested, construction of roads and railways is difficult which

brings the problem of communication can help to transport agricultural products.

- Thickness of the vegetation as seen from the picture make the clearing of the land for

farming very difficult

- The way the vegetation appears, dangerous animals such as snakes can call it home.

Such animals including pests such as tsetse flies can spread diseases to both people

and animals.

- Thickness of the vegetation is as a result of heavy rainfall. Such rainfall usually wash

the fertile soil away through leaching.

Why is the vegetation in B have the following:

Buttress roots- these help to support the tall tress

Dark green and leathery leaves- preventing the wilting during the hottest

part of the day

Shining surface of the leaves- help to shed water quickly so that

transpiration is not hindered

Study the photograph below of a vegetation type (1994)

Photo

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Name the vegetation type depicted in the photograph

It is Xerophytes desert vegetation

Suggest the names of the plants labeled A and B in the Photograph

A= thorny or porcupine bushes

B= cacti/ cactus

From your knowledge suggest the latitudinal location of this type of vegetation

Located on the western sides of the continents between 15

0

and 30

0

North or South

of the equator

Name any two areas in the Southern Hemisphere which have this type of vegetation

- Kalahari desert

- Namibia desert

- Atacama desert

- The great Australian desert

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NOTE: if the vegetation would require in the northern hemisphere, Mohave, Gobi, and

Sahara would be the prominent examples.

Explain any three ways in which plants are adapted to the temperature and precipitation

conditions prevalent in the environment

- Have waxy and tiny leaves in order to prevent transpiration due to high temperatures

- Produce sleepy seeds that lie dormant during dry months and germinate when water is

available

- Grow log and spreading searching roots in order to look for water under the ground as the

water is scarce

- Have very thick and succulent stems which usually keep water

Name any two types of agricultural systems practiced in this type of environment

- Irrigation farming especially in oases. These are places where water flows on its own in

deserts as a result of water table being closer to the surface. Wheat, dates, vegetables and

fruits are grown.

- Pastoralism by nomadic tribes especially in the Sahara and the Arabian deserts. Sheep,

cattle, goats are kept for meat and milk.

Explain two limiting factors that this type of environment has on agricultural development

- Very limited quantities and distribution of available fresh water to be used in irrigation

- Rainfall is very scarce to support the cultivation of crops

- The soils are very poor , composed of trees, not suitable for the cultivation of crops

- Very high temperatures make crops to wilt.

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THE ENVIRONEMNT, DESERTIFICATION, WETLANDS, ENDANGERED SPECIES,

CLIMATIC CHANGE

Define the word “ desertification”

This refers to the process that creates desert conditions by down grading the land

surface

Why is desertification sometimes defined as “ creeping desert” (1992)

Because it is steady process that turns good and fertile land into a barren one usually

as as a result of human activities to the environment.

Explain any three causes of desertification in Africa (2002) (6 marks) (2007)

- The demand for wood for fire especially in developing countries. Trees and shrubs are

removed making the soil to become vulnerable to erosion by wind and water. This

downgrades the land.

- Over cultivation as a result of rapid population growth which results into increased

pressure on farmland. This makes people to cultivate in marginal areas such as catchment

areas, riverbanks which are more vulnerable to erosion and makes rivers to dry up easily.

- Having large numbers of livestock gathering in watery holes which leads to overgrazing

and degradation of vegetation especially in pastoral nomadism

- Deforestation which is the felling and clearance of forest land for cultivation and

settlement. The land is eventually left bare.

Outline four problems associate with desertification in Africa (2000) (2007)

- It disturbs the water cycle since the rate of transpiration is tampered with. This may lead

to a series of drought and famine conditions as crops cannot be cultivated.

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- Results into soil erosion, as the soil is left bare due to the removal of forests. This makes

the soil to be degraded leading to low crop yields.

- Results into climatic change due to a lot of heat on the earth’s surface

- As the ground is not protected it results into floods that destroy a lot of property and life.

- Prevents vegetation of various species of plants which eventually becomes extinct.

Suggest three solutions to some of the problems of desertification in Africa (2002)

- A forestation which involves the planting of trees where there were not trees. This apart

from protecting the soil from erosion, it will make transpiration to take place normally.

- Reafforestation which is a tendency of planting trees where they have been cut down

- Controlling rapid population growth through good health measures. This will reduce the

pressure on vegetation thus combating desertification.

How do the following ways help to control desertification?

Civic education: this sensitise opeople on the importance of managing the

environment properly and the bad results of it. When people are aware, they

will not do anything bad out of ignorance and this helps to control

desertification

Proper land husbandry: by following good farming practices such as

constructing ridges across the slope, avoiding overgrazing and over stocking,

desertification is combated as the land is protected from erosion agents of

water and wind.

Provision of alternative sources of energy such as solar, hydro and wind:

this reduces pressure on vegetation as a reliable source of energy and in this

way combats desertification especially in rural areas where people are not

exposed to such alternative sources of energy but only depend on fuel wood.

State any three ways in which deforestation can be combated

- Aforestation

- Reaforestation

- Provision of alternative sources of energy such as hydro

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- Civic educating campaigns on the importance of vegetation

Name three countries in west Africa where desertification is a serious problem 93) (1992)

Mali, Burkina Faso, Mauritania, Senegal (mostly in the Sahel region)

Describe the process of desertification

The process of desertification starts with the increase in human population. This

creates the demand for land for settlement, cultivation and as source of energy. This

then results into deforestation, over cultivation, over grazing and over stocking. This

in turn results into soil erosion, climatic change, drought and eventually a desert.

Figure A and B on the next page shows the effects of desertification in the Sahel region of

West Africa. Study the photographs and answer the questions that follow (1992)

Photos

Chech pp nwachukwu

State what you see of the natural vegetation in both photographs

The natural vegetation has been completely removed as no trees or grasses can be

seen in the pictures except sand, and some small sticks which show that at first the

place had some trees.

From evidence provided by the two photographs, describe two problems arising from

desertification

The photographs show women carrying firewood and a cow lying dead. This shows

that an increase in population puts pressure on the vegetation for fuel wood. This in

turn result into deforestation, leaving the land bare as the picture shows. An increase

in population creates a demand for meat. This contributes to overgrazing and over

stocking. These results into shortage of grass for animals and water to drink, hence

the death of animals as picture B shows.

Page 150 of 159

Describe three human activities that might have led to the results of observed in the figures

- Having large numbers of livestock gathering in water places which contributes to

overgrazing and overstocking as the picture B shows.

- The demand for wood for fire especially in developing countries. This puts pressure on

trees such that at a climax, it becomes even possible for women to travel long distances in

search of firewood in the tropical scotching heat as the picture A suggests.

- Climate change which is a direct consequences of human beings mismanaging the

environment. This brings about drought conditions which are characterized by dry

conditions as shown in the pictures A and B

Why is desertification becoming a threat in Malawi?

This is because the population is increasing rapidly in Malawi. This makes forests to

be cleared for cultivation, settlements apart from fuel wood, which is definitely

bringing desert conditions with floods, poor soils, erosion, death of animals such as

cattle, difficulties in obtaining fuel wood as the possible signs.

ENDANGERED SPEIESC, WETLANDS

Define the term “endangered species”

This refers to the scarcity and extinction of certain plants and animals in the

environment as a result of human activities.

Explain four ways in which species are endangered in the environment

- Poor agricultural practices such as shifting cultivation, pastoral nomadism, and making

ridges along the slopes. These endanger wild and aquatic life species in the sense that

they destroy the habitat for wild life like in the case of shifting cultivation that destroy the

vegetation in which animals take refuge.

- Deforestation which refers to the wanton cutting down of trees without replacement.

This endangers wild and aquatic species in that it encourages greater run off and large

scale erosion which degrades and destroys the habitat for wild life.

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- Misuse of pesticides which destroy the habitat and kill aquatic animals when discharged

into water. Some chemicals when discharged in water kill aquatic life directly when

poisonous or deny aquatic life of oxygen making them to suffocate and die.

- Poor waste disposal by industries and human beings. This may bring diseases which kill

animals and plants

- Disruption of the food chain. Killing or getting rid of one or two species of living

organisms affects the life expectancy of the others. This reduces and eventually leads to

the extinction of plants and animals due to lack of food for them. For example, the

removal of buffaloes in the environment can result into the extinction of lions which

depend on buffaloes for food.

- Over fishing which refers to the catching of fish faster than that which can be replaced

through reproduction. This result into the reduction and scarcity of some fish species like

chambo which consequently leads to extinction.

- Poaching which refers to the illegal killing of animals especially in protected areas. This

comes largely because of rapid population growth which can result into depletion or

reduction and extinction of wild life.

- Draining of marshes and swamps. This destroys the habitat for marine species like

crocodiles hippopotamus, fish, water birds like cormorant.

Explain how the following points endanger plants and animal species:

Genetic modification or hybridization

This is the cross breeding of two or more species in order to produce one. The

produced specie takes the characteristics of these two or more species cross-

bred. This endangers the plant or animal species in the sense that the such

species replace the original species which then becomes vanished from the

environment.

Introduction of the exotic species into local habitats

This endangers the species in the sense that the exotic, introduced species

destroy and dominate the endemic species which eventually vanishes from the

environment.

war

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This tends to harvest species in unsustainable manner by over harvesting species

due to lack of control.

Habitat destruction

This tend to quicken the disappearance of species by limiting space in which a

species can be accommodated and nourished

Climate change

This tend to raise or lower temperatures, thus making adaptation of species

very difficult and as a result the species die off completely

How are the following species endangered from the environment:

Trees:- through deforestation, harmful bushfires, mining, quarrying which

completely removes trees.

Fish such as Tuna, cod and chambo

This is done through overfishing, destruction of fishing grounds, polluting

water bodies and through fish piracy. These remove the species in water

bodies such as rivers, lakes and seas.

Elephants: through poaching in game parks. Poachers look for tusks or ivory

and to a lesser extent meat

Birds: through human settlement that destroy the habitat, predation,

deforestation and harmful bushfires which even kill the young birds apart

from destroying the food for the old ones. Some colorful birds are smuggled

to outside.

Gorillas: encroachment into their habitat through opening gardens and

settlements. Poaching whereby they are killed for their skins. Some are even

smuggled to other countries to be used in the tourism industry.

Black rhinos: these are removed through poaching as the poachers target their

horns which are then sold overseas and the whole body is just kept

Lions, leopards: these are poached for their skins which are sold overseas.

Buffaloes: these are poached for both meat and hides

Explain two ways in which wild and aquatic life species is of importance

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- These promote tourism which in turn improves foreign exchange currency as tourists visit

places of interest

- They are source of protein, calcium, and other nutrients which are important in the body

of human beings

- Source of income to people. For instance, people go fishing and eventually find money

- They bring about an ecological balance.

Explain some of the ways in which the following can be conserved:

Aquatic species

- Protection of rare endangered species by establishing some strict rules. For example,

those fishermen catching chambo fish, should be throwing it back in water because it is a

rare and endangered specie

- Avoid over fishing by introducing a closed season whereby fishing is not allowed during

the breeding season.

- Civic educating the people in the dangers of removing the aquatic life and the importance

of conserving them.

Wild species

- Establishment of conservation areas such as forest reserves, national parks and game

reserves.

- Catching game where they are facing extinction or overpopulation and relocating them

elsewhere

- Civic educating the masses especially those around the protected areas on the importance

of protected areas and the wild life contained.

- Harsh penalties for those who deliberately bend the rules for conserving wildlife. For

example, poaches to get stiffer punishments so that others should learn a lesson from

them.

Explain the importance of each of the following practices in the environment:-

Proper land husbandry

This helps to maintain the vegetation thereby preventing soil erosion that

leads to silt built up and poor soil fertility

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Maintaining crocodiles in their natural settings

This helps to maintain the food chain in the environment thereby making

some species to survive in the environment.

Correct amount of greenhouse gases in the atmosphere

This makes the ozone layers not to be destroyed. When the ozone has not been

destroyed, the gamma rays, the infrared and the X- rays would not reach the

earth’s thereby causing global warming. Global warming make some plant

and animal species to become extinct.

WETLNADS

Define wetlands

This refers to swamps, marshes and bogs where water remains stagnant for a greater

part of the year.

In what two ways can wetlands be important to society?

- They are habitat for birds, and endangered and threatened plant and fish species

- They beautify the environment, providing grounds where biological studies and

recreational observation can take place.

- They are centers of tourism that bring much needed foreign currency to a country

- They produce life in that they provide feeding, spawning and nursery for fish

Explain two ways in which wetlands are a source of clean water (2006)

- Wetlands absorb and filter pollutants that would degrade rivers and lakes, thus providing

clean water.

- Wetlands hold back the excess water that would cause flooding. This also help to clean

up the water as the flooded water is not clean.

Describe the positive impact that wetlands have on global warming (2006)

Wetlands help to lock up carbon inform of peat and prevent it from entering the

atmosphere as carbon dioxide, the main gas in global warming.

Draw a map of Malawi. On it locate and name two examples of wetlands

Map

Page 155 of 159

Get it from phy geo

2. How can the following help to manage wetlands in Malawi:-

a. Government

The government can civic educate people living near and around wetlands on

the importance of these areas. The government, apart form passing stringiest

laws to protect such places, it can also teach people to control population

growth which gives pressure on the land.

b. Individual

Individual’s should avoid encroaching wetlands by not draining them. It is

only knowledgeable people who are able to do so. This is where civic

education becomes important.

c. Communities

Civic education should be done within the communities in addition to the

communities joining hands in protecting the wetlands by ensuring that anyone

found encroaching them is dealt with accordingly.

Give two examples of human activities that can threaten wetlands

- Draining them away for using the land for cultivation

- Constructing settlements in such important areas.

- Planting rice in wetlands

- Catching fish in such areas

Give two problems that the people living close to wetlands are likely to face

- Malarial problems as the wetlands act as bleeding places for mosquitoes which transmit

malaria

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- Some animals which live in such places may destroy peoples crops. For example

elephants in Vwaza marsh.

Suppose the government wants to drain all the wetlands. Suggest two problems that would

be experienced as a result of this action by government

- Wetlands help in flood control. Swamps hold back water or run off, thus controlling

floods. Removal of these would speed up the storm flow and results into flooding,

destroying life and property. For example, the ndindi and elephant marshes in the lower

shire help to reduce the occurrence of flooding.

- There would be the extinction of some plants and animals which use such places as

habitats

- There would be a decline in the tourism industry. Some wetlands such as Vwaza marsh,

Elephant marsh help to attract tourists. The much needed foreign currency generated

through tourism would go down.

- It would increase the global warming. This is because the carbon locked up in form of

peat in these area would release a lot of carbon dioxide, the main gas in global warming.

Explain the word “ climate change”

This is the change in the world climate due to human activities done to the

environment

Explain two causes of climatic change

- Deforestation which is the wanton cutting down of trees for settlements and cultivation.

This is due to rapid population growth. This results into the climatic change because the

rate of transpiration is reduced leading to little or not rainfall.

- The release of gases such as carbon dioxide, methane and chloroflourocarbons (CFCs)

from refrigerators. These do not only destroy the ozone layer thereby allowing ultraviolet

rays to reach the earth, but also cause global warming as the stop the rays form going

back into the atmosphere. This upsets normal trend of rainfall. High temperatures also

disturb the condensation point as the dew point is not reached easily.

3. Explain why three effects of climate change (in what three ways is climatic

change bad to the planet earth) (give three things that can be the signs to show

that the climate has really changed)

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- Global warming: this is the warming up of the earth due to inability of the heat to escape

into the space. This is caused by the greenhouse gases such as carbon dioxide, methane

and chlorofloro carbons. These gases cause global warming in the sense that they attack

the ozone layer and destroy it. Rays from the sun such as the gamma rays, infrared rays

and X-rays reach the earth. This increases the temperature. Apart form this, the gases trap

the reflected rays from the earth and send them back, further increasing the temperature

hence global warming. This apart from making some plant and animal species to die out,

it affects evapotranspiration and condensation thereby tampering with the water cycle,

bringing drought conditions or heavy rainfall that cause floods.

- It results into an increase in storm cyclones develop as a result of a low pressure. This

low pressure develops as a result of temperature. Tropical storms such as the hurricanes,

the cyclones and the Willy willies destroy property and infrastructure.

- Results into change in the direction of flow of ocean currents. Usually warm ocean

currents from the Polar Regions. With increase in temperature the direction of such ocean

currents change which results into the change in climate as ocean currents influence the

climate of an area.

- The shrinking of the Antarctic Ice cap. The increase in temperature makes ice to melt in

Polar Regions. This leads to flooding as the molten water gets into water masses.

Explain some three ways that the government can do in order to reduce the effects of

climatic change

- Sensitization campaigns through world organizations and governments. Communities in

different parts fo the world should be civic educated on the problems of climate change.

- Avoidance of use of machines or activities that release dangerous gases such as

chloroflorocarborns, methane and carbon dioxide. This will help to maintain the ozone

layer and stop global warming.

- Avoidance of setting harmful bushfires. This adds a lot of carbon dioxide that contribute

to global warming.

Explain three effects of global warming

- Hot areas become hotter which help in the spread of desertification

- The melting of glaciers that cause flooding especially in low lying areas such as

Netherlands

- Spreading tropical diseases to the temperate regions

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- Shifting climatic belts and vegetation types and in the process some plants and animals

being lost forever.

Explain any two ways in which undisturbed climate in Malawi could act as a conservation

measures for wildlife (2006) (4)

- It could not result into flooding that would destroy wildlife and property

- It could reduce the occurrence of drought that would lead into the death of and extinction

of wildlife.

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